Refactor parsing pt5

CHANGELOG.md

@@ -8,7 +8,6 @@
     codegen section can focus only in codegen, not in
     translation of thp->php.
 - Parse __more__ binary operators
-- Parse `Type name = value` bindings
 - Parse more complex bindings
 - Watch mode
 - Improve error messages
@@ -23,18 +22,40 @@
 - Simple language server
 - Decide how to handle comments in the syntax (?)(should comments mean something like in rust?)
 
+## v0.0.12
+
+- [ ] Infer datatype of a function call expression
+- [ ] Infer datatype of binary operators
+- [ ] Execute semantic analysis on the function's block
+- [ ] Write tests
+
+
+## v0.0.11
+
+- [ ] Parse binding of form `val Type variable = value`
+- [ ] Parse binding of form `Type variable = value`
+- [ ] Infer datatype of `value` in the above for a simple expression
+- [ ] Ensure that the anotated datatype matches the datatype of `value` in the above
+- [ ] Infer datatype of a `val variable = value` in the AST: Use the infered datatype
+- [ ] Formally define the top level constructs
+- [ ] Parse bindings and function declarations as top level constructs
+- [ ] Parse function declaration arguments (`Type id`)
+- [ ] Parse function return datatype (`fun f() -> Type`)
+- [ ] Return parsing to variables to var/val
+- [ ] Write tests
+
+
 ## v0.0.10
 
 - [x] Parse function call parameters
 - [x] Codegen function call parameters
-- [x] Parse function declaration arguments (Type id)
 - [x] Begin work on semantic analysis
 - [x] Minimal symbol table
 - [x] Check duplicate function declarations
 - [x] Improve REPL/File compilation code
-- [ ] Typecheck bindings
+- [x] Check binding duplication in it's scope
-- [x] Typecheck functions
+- [x] Check function duplication in it's scope
-- [ ] Transform simple THP expression into PHP statements
+- [x] Transform simple THP expression into PHP statements
 
 ## v0.0.9
 

src/codegen/binding.rs

@@ -1,28 +1,36 @@
 use super::Transpilable;
 use crate::syntax::ast::var_binding::Binding;
 
-impl Transpilable for Binding {
+impl Transpilable for Binding<'_> {
     /// Transpiles val and var bindings into PHP.
     fn transpile(&self) -> String {
         let expression_str = self.expression.transpile();
 
-        format!("${} = {}", self.identifier, expression_str)
+        format!("${} = {}", self.identifier.value, expression_str)
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::syntax::ast::{var_binding::Binding, Expression};
+    use crate::{
+        lexic::token::{Token, TokenType},
+        syntax::ast::{var_binding::Binding, Expression},
+    };
 
     #[test]
     fn binding_should_transpile() {
         let id = String::from("identifier");
+        let id_token = Token {
+            token_type: TokenType::Identifier,
+            value: id,
+            position: 0,
+        };
         let value = String::from("322");
         let binding = Binding {
             datatype: None,
-            identifier: Box::new(id),
+            identifier: &id_token,
-            expression: Expression::Number(Box::new(value)),
+            expression: Expression::Number(&value),
             is_mutable: false,
         };
 

src/codegen/block.rs

@@ -2,7 +2,7 @@ use crate::syntax::ast::Block;
 
 use super::Transpilable;
 
-impl Transpilable for Block {
+impl Transpilable for Block<'_> {
     fn transpile(&self) -> String {
         // TODO: Handle indentation
         self.statements

src/codegen/expression.rs

@@ -1,7 +1,7 @@
 use super::Transpilable;
 use crate::syntax::ast::Expression;
 
-impl Transpilable for Expression {
+impl Transpilable for Expression<'_> {
     /// Transpiles an Expression to PHP
     ///
     /// Right now the expressions in the grammar are:
@@ -41,7 +41,7 @@ mod tests {
     #[test]
     fn should_transpile_number() {
         let str = String::from("42");
-        let exp = Expression::Number(Box::new(str));
+        let exp = Expression::Number(&str);
         let result = exp.transpile();
 
         assert_eq!("42", result);
@@ -50,7 +50,7 @@ mod tests {
     #[test]
     fn should_transpile_string() {
         let str = String::from("\"Hello world\"");
-        let exp = Expression::String(Box::new(str));
+        let exp = Expression::String(&str);
         let result = exp.transpile();
 
         assert_eq!("\"Hello world\"", result);
@@ -67,7 +67,7 @@ mod tests {
     #[test]
     fn should_transpile_identifier() {
         let s = String::from("newValue");
-        let exp = Expression::Identifier(Box::new(s));
+        let exp = Expression::Identifier(&s);
         let result = exp.transpile();
 
         assert_eq!("newValue", result);

src/codegen/function_call.rs

@@ -2,7 +2,7 @@ use crate::syntax::ast::functions::FunctionCall;
 
 use super::Transpilable;
 
-impl Transpilable for FunctionCall {
+impl Transpilable for FunctionCall<'_> {
     fn transpile(&self) -> String {
         let parameters = &self
             .arguments

src/codegen/function_declaration.rs

@@ -2,11 +2,11 @@ use crate::syntax::ast::FunctionDeclaration;
 
 use super::Transpilable;
 
-impl Transpilable for FunctionDeclaration {
+impl Transpilable for FunctionDeclaration<'_> {
     fn transpile(&self) -> String {
         format!(
             "function {}() {{\n{}\n}}",
-            self.identifier,
+            self.identifier.value,
             self.block.transpile()
         )
     }
@@ -34,6 +34,7 @@ mod tests {
 
                 assert_eq!("function id() {\n\n}", transpiled);
             }
+            _ => panic!("Not implemented: Expression at top level"),
         }
     }
 }

src/codegen/module_ast.rs

@@ -1,7 +1,7 @@
 use super::Transpilable;
 use crate::syntax::ast::ModuleAST;
 
-impl Transpilable for ModuleAST {
+impl Transpilable for ModuleAST<'_> {
     /// Transpiles the whole AST into PHP, using this same trait on the
     /// nodes and leaves of the AST
     fn transpile(&self) -> String {
@@ -18,16 +18,24 @@ impl Transpilable for ModuleAST {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::syntax::ast::{var_binding::Binding, Expression, TopLevelDeclaration};
+    use crate::{
+        lexic::token::{Token, TokenType},
+        syntax::ast::{var_binding::Binding, Expression, TopLevelDeclaration},
+    };
 
     #[test]
     fn module_ast_should_transpile() {
         let id = String::from("identifier");
+        let id_token = Token {
+            token_type: TokenType::Identifier,
+            value: id,
+            position: 0,
+        };
         let value = String::from("322");
         let binding = Binding {
             datatype: None,
-            identifier: Box::new(id),
+            identifier: &id_token,
-            expression: Expression::Number(Box::new(value)),
+            expression: Expression::Number(&value),
             is_mutable: false,
         };
 

src/codegen/statement.rs

@@ -2,7 +2,7 @@ use crate::syntax::ast::statement::Statement;
 
 use super::Transpilable;
 
-impl Transpilable for Statement {
+impl Transpilable for Statement<'_> {
     fn transpile(&self) -> String {
         let stmt = match self {
             Statement::FunctionCall(f) => f.transpile(),

src/codegen/top_level_construct.rs

@@ -2,11 +2,12 @@ use crate::syntax::ast::TopLevelDeclaration;
 
 use super::Transpilable;
 
-impl Transpilable for TopLevelDeclaration {
+impl Transpilable for TopLevelDeclaration<'_> {
     fn transpile(&self) -> String {
         match self {
             TopLevelDeclaration::Binding(binding) => binding.transpile(),
             TopLevelDeclaration::FunctionDeclaration(fun) => fun.transpile(),
+            _ => panic!("Not implemented: Expression at top level"),
         }
     }
 }

src/lexic/token.rs

@@ -22,7 +22,7 @@ pub enum TokenType {
     FUN,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Token {
     pub token_type: TokenType,
     // The token as a raw string

src/main.rs

@@ -13,7 +13,6 @@ mod lexic;
 mod semantic;
 // Transforms an AST to JS
 mod codegen;
-mod utils;
 
 mod error_handling;
 

src/semantic/impls.rs

@@ -4,13 +4,13 @@ use crate::{
     syntax::ast::{ModuleAST, TopLevelDeclaration},
 };
 
-use super::symbol_table::SymbolTable;
+use super::symbol_table::{SymbolEntry, SymbolTable};
 
 pub trait SemanticCheck {
     fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError>;
 }
 
-impl SemanticCheck for ModuleAST {
+impl SemanticCheck for ModuleAST<'_> {
     /// Checks that this AST is semantically correct, given a symbol table
     fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
         for declaration in &self.declarations {
@@ -21,28 +21,60 @@ impl SemanticCheck for ModuleAST {
     }
 }
 
-impl SemanticCheck for TopLevelDeclaration {
+impl SemanticCheck for TopLevelDeclaration<'_> {
     fn check_semantics(&self, scope: &SymbolTable) -> Result<(), MistiError> {
         match self {
-            TopLevelDeclaration::Binding(_) => {
+            TopLevelDeclaration::Binding(binding) => {
+                let binding_name = &binding.identifier.value;
+
+                if scope.test(binding_name) {
                     let error = SemanticError {
-                    error_start: 0,
+                        error_start: binding.identifier.position,
-                    error_end: 0,
+                        error_end: binding.identifier.get_end_position(),
-                    reason: "Binding typechecking: Not implemented".into(),
+                        reason: format!(
+                            "Duplicated function: A function with name {} was already defined",
+                            binding_name
+                        ),
                     };
 
-                Err(MistiError::Semantic(error))
+                    return Err(MistiError::Semantic(error));
+                }
+
+                let datatype = match binding.datatype {
+                    Some(t) => t,
+                    None => {
+                        let error = SemanticError {
+                            error_start: binding.identifier.position,
+                            error_end: binding.identifier.get_end_position(),
+                            reason: format!(
+                                "The variable `{}` didn't define a datatype. Datatype inference is not implemented.",
+                                binding_name
+                            ),
+                        };
+
+                        return Err(MistiError::Semantic(error));
+                    }
+                };
+
+                scope.insert(
+                    binding_name.clone(),
+                    SymbolEntry::new_variable(datatype.value.clone()),
+                );
+
+                Ok(())
             }
             TopLevelDeclaration::FunctionDeclaration(function) => {
-                let function_name = function.identifier.as_ref().clone();
+                let function_name = function.identifier.value.clone();
 
+                // Check that the function is not already defined
                 if scope.test(&function_name) {
                     let error = SemanticError {
-                        // TODO: Get the position of the function name. For this, these structs
+                        error_start: function.identifier.position,
-                        // should store the token instead of just the string
+                        error_end: function.identifier.get_end_position(),
-                        error_start: 0,
+                        reason: format!(
-                        error_end: 0,
+                            "Duplicated function: A function with name {} was already defined",
-                        reason: format!("Function {} already defined", function_name),
+                            function_name
+                        ),
                     };
 
                     return Err(MistiError::Semantic(error));
@@ -50,11 +82,12 @@ impl SemanticCheck for TopLevelDeclaration {
 
                 scope.insert(
                     function_name,
-                    super::symbol_table::SymbolEntry::Function(vec![], "Unit".into()),
+                    SymbolEntry::new_function(vec![], "Unit".into()),
                 );
 
                 Ok(())
             }
+            _ => panic!("Not implemented"),
         }
     }
 }

src/syntax/ast/functions.rs

@@ -1,12 +1,12 @@
 use super::Expression;
 
 #[derive(Debug)]
-pub struct FunctionCall {
+pub struct FunctionCall<'a> {
-    pub function: Box<Expression>,
+    pub function: Box<Expression<'a>>,
-    pub arguments: Box<ArgumentsList>,
+    pub arguments: Box<ArgumentsList<'a>>,
 }
 
 #[derive(Debug)]
-pub struct ArgumentsList {
+pub struct ArgumentsList<'a> {
-    pub arguments: Vec<Expression>,
+    pub arguments: Vec<Expression<'a>>,
 }

src/syntax/ast/mod.rs

@@ -1,46 +1,49 @@
+use crate::lexic::token::Token;
+
 use self::functions::FunctionCall;
 
 pub mod functions;
 pub mod statement;
 pub mod var_binding;
 
-pub struct ModuleAST {
+pub struct ModuleAST<'a> {
-    pub declarations: Vec<TopLevelDeclaration>,
+    pub declarations: Vec<TopLevelDeclaration<'a>>,
 }
 
 #[derive(Debug)]
-pub enum TopLevelDeclaration {
+pub enum TopLevelDeclaration<'a> {
-    Binding(var_binding::Binding),
+    Binding(var_binding::Binding<'a>),
-    FunctionDeclaration(FunctionDeclaration),
+    FunctionDeclaration(FunctionDeclaration<'a>),
+    Expression(Expression<'a>),
 }
 
 #[derive(Debug)]
-pub struct FunctionDeclaration {
+pub struct FunctionDeclaration<'a> {
-    pub identifier: Box<String>,
+    pub identifier: &'a Token,
     pub params_list: Box<ParamsList>,
-    pub block: Box<Block>,
+    pub block: Box<Block<'a>>,
 }
 
 #[derive(Debug)]
-pub struct Block {
+pub struct Block<'a> {
-    pub statements: Vec<statement::Statement>,
+    pub statements: Vec<statement::Statement<'a>>,
 }
 
 #[derive(Debug)]
 pub struct ParamsList {}
 
-pub struct Parameter {
+pub struct Parameter<'a> {
-    pub identifier: Box<String>,
+    pub identifier: &'a String,
-    pub datatype: Box<String>,
+    pub datatype: &'a String,
 }
 
 #[derive(Debug)]
-pub enum Expression {
+pub enum Expression<'a> {
-    Number(Box<String>),
+    Number(&'a String),
-    String(Box<String>),
+    String(&'a String),
     Boolean(bool),
-    Identifier(Box<String>),
+    Identifier(&'a String),
-    FunctionCall(FunctionCall),
+    FunctionCall(FunctionCall<'a>),
-    UnaryOperator(Box<String>, Box<Expression>),
+    UnaryOperator(&'a String, Box<Expression<'a>>),
-    BinaryOperator(Box<Expression>, Box<Expression>, Box<String>),
+    BinaryOperator(Box<Expression<'a>>, Box<Expression<'a>>, &'a String),
 }

src/syntax/ast/statement.rs

@@ -1,7 +1,7 @@
 use super::{functions::FunctionCall, var_binding::Binding};
 
 #[derive(Debug)]
-pub enum Statement {
+pub enum Statement<'a> {
-    FunctionCall(FunctionCall),
+    FunctionCall(FunctionCall<'a>),
-    Binding(Binding),
+    Binding(Binding<'a>),
 }

src/syntax/ast/var_binding.rs

@@ -1,9 +1,11 @@
+use crate::lexic::token::Token;
+
 use super::Expression;
 
 #[derive(Debug)]
-pub struct Binding {
+pub struct Binding<'a> {
-    pub datatype: Option<String>,
+    pub datatype: Option<&'a Token>,
-    pub identifier: Box<String>,
+    pub identifier: &'a Token,
-    pub expression: Expression,
+    pub expression: Expression<'a>,
     pub is_mutable: bool,
 }

src/syntax/binding.rs

@@ -1,14 +1,14 @@
 use super::ast::var_binding::Binding;
 use super::utils::{parse_token_type, try_operator};
-use super::{expression, ParseResult};
+use super::{expression, ParsingError, ParsingResult};
 use crate::error_handling::SyntaxError;
 use crate::lexic::token::{Token, TokenType};
-use crate::utils::Result3;
 
-pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Binding, ()> {
+pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Binding> {
     let mut current_pos = pos;
 
     // TODO: Detect if the binding starts with a datatype
+    // TODO: Revert to val/var
 
     /*
      * let keyword
@@ -16,14 +16,14 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Binding,
     let (is_mutable, binding_token, next_pos) = {
         let let_token = parse_token_type(tokens, current_pos, TokenType::LET);
         match let_token {
-            ParseResult::Ok(let_token, next_let) => {
+            Ok((let_token, next_let)) => {
                 let mut_token = parse_token_type(tokens, next_let, TokenType::MUT);
                 match mut_token {
-                    ParseResult::Ok(_mut_token, next_mut) => (true, let_token, next_mut),
+                    Ok((_mut_token, next_mut)) => (true, let_token, next_mut),
                     _ => (false, let_token, next_let),
                 }
             }
-            _ => return ParseResult::Unmatched,
+            _ => return Err(ParsingError::Unmatched),
         }
     };
     current_pos = next_pos;
@@ -33,28 +33,28 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Binding,
      */
     let (identifier, next_pos) = match parse_token_type(tokens, current_pos, TokenType::Identifier)
     {
-        ParseResult::Ok(t, n) => (t, n),
+        Ok((t, n)) => (t, n),
-        ParseResult::Mismatch(token) => {
+        Err(ParsingError::Mismatch(token)) => {
             // The parser found a token, but it's not an identifier
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 error_start: token.position,
                 error_end: token.get_end_position(),
                 reason: "??".into(),
-            });
+            }));
         }
-        ParseResult::Err(error) => {
+        Err(ParsingError::Err(error)) => {
-            return ParseResult::Err(error);
+            return Err(ParsingError::Err(error));
         }
         _ => {
             // The parser didn't find an Identifier after VAL/VAR
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: format!(
                     "There should be an identifier after a `{}` token",
                     if is_mutable { "val" } else { "var" }
                 ),
                 error_start: binding_token.position,
                 error_end: binding_token.get_end_position(),
-            });
+            }));
         }
     };
     current_pos = next_pos;
@@ -63,67 +63,67 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Binding,
      * Equal (=) operator
      */
     let equal_operator = match try_operator(tokens, current_pos, String::from("=")) {
-        Result3::Ok(t) => t,
+        Ok((t, _)) => t,
-        Result3::Err(t) => {
+        Err(ParsingError::Mismatch(t)) => {
             // The parser found a token, but it's not the `=` operator
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: format!("There should be an equal sign `=` after the identifier"),
                 error_start: t.position,
                 error_end: t.get_end_position(),
-            });
+            }));
         }
-        Result3::None => {
+        _ => {
             // The parser didn't find the `=` operator after the identifier
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: format!("There should be an equal sign `=` after the identifier",),
                 error_start: identifier.position,
                 error_end: identifier.get_end_position(),
-            });
+            }));
         }
     };
     current_pos += 1;
 
     let (expression, next_pos) = match expression::try_parse(tokens, current_pos) {
-        ParseResult::Ok(exp, next) => (exp, next),
+        Ok((exp, next)) => (exp, next),
         _ => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected an expression after the equal `=` operator"),
                 error_start: equal_operator.position,
                 error_end: equal_operator.get_end_position(),
-            });
+            }));
         }
     };
     current_pos = next_pos;
 
     let binding = Binding {
         datatype: None,
-        identifier: Box::new(identifier.value.clone()),
+        identifier: &identifier,
         expression,
         is_mutable,
     };
 
-    ParseResult::Ok(binding, current_pos)
+    Ok((binding, current_pos))
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{lexic::get_tokens, syntax::utils::try_token_type};
+    use crate::{lexic::get_tokens, syntax::utils::parse_token_type};
 
     #[test]
     fn should_parse_val_binding() {
         let tokens = get_tokens(&String::from("let identifier = 20")).unwrap();
-        let ParseResult::Ok(binding, _) = try_parse(&tokens, 0) else {
+        let Ok((binding, _)) = try_parse(&tokens, 0) else {
             panic!()
         };
 
-        assert_eq!("identifier", format!("{}", binding.identifier));
+        assert_eq!("identifier", format!("{}", binding.identifier.value));
     }
 
     #[test]
     fn should_parse_val() {
         let tokens = get_tokens(&String::from("let")).unwrap();
-        let token = *try_token_type(&tokens, 0, TokenType::LET).unwrap();
+        let (token, _) = parse_token_type(&tokens, 0, TokenType::LET).unwrap();
 
         assert_eq!(TokenType::LET, token.token_type);
         assert_eq!("let", token.value);
@@ -132,7 +132,7 @@ mod tests {
     #[test]
     fn should_parse_identifier() {
         let tokens = get_tokens(&String::from("identifier")).unwrap();
-        let token = *try_token_type(&tokens, 0, TokenType::Identifier).unwrap();
+        let (token, _) = parse_token_type(&tokens, 0, TokenType::Identifier).unwrap();
 
         assert_eq!("identifier", token.value);
     }
@@ -140,7 +140,7 @@ mod tests {
     #[test]
     fn should_parse_operator() {
         let tokens = get_tokens(&String::from("=")).unwrap();
-        let token = *try_operator(&tokens, 0, String::from("=")).unwrap();
+        let (token, _) = try_operator(&tokens, 0, String::from("=")).unwrap();
 
         assert_eq!("=", token.value);
     }
@@ -174,7 +174,7 @@ mod tests {
         let binding = try_parse(&tokens, 0);
 
         match binding {
-            ParseResult::Err(error) => {
+            Err(ParsingError::Err(error)) => {
                 assert_eq!(0, error.error_start);
                 assert_eq!(3, error.error_end);
             }
@@ -190,7 +190,7 @@ mod tests {
         let binding = try_parse(&tokens, 0);
 
         match binding {
-            ParseResult::Err(error) => {
+            Err(ParsingError::Err(error)) => {
                 assert_eq!(4, error.error_start);
                 assert_eq!(7, error.error_end);
             }
@@ -201,7 +201,7 @@ mod tests {
         let binding = try_parse(&tokens, 0);
 
         match binding {
-            ParseResult::Err(error) => {
+            Err(ParsingError::Err(error)) => {
                 assert_eq!(4, error.error_start);
                 assert_eq!(11, error.error_end);
             }
@@ -215,7 +215,7 @@ mod tests {
         let binding = try_parse(&tokens, 0);
 
         match binding {
-            ParseResult::Err(error) => {
+            Err(ParsingError::Err(error)) => {
                 assert_eq!(7, error.error_start);
                 assert_eq!(14, error.error_end);
             }

src/syntax/block.rs

@@ -3,19 +3,13 @@ use crate::{
     lexic::token::{Token, TokenType},
 };
 
-use super::{ast::Block, utils::parse_token_type, ParseResult};
+use super::{ast::Block, utils::parse_token_type, ParsingError, ParsingResult};
 
 // Assumes that the token at `pos` is a {
-pub fn parse_block<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Block, &Token> {
+pub fn parse_block<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Block> {
     let mut current_pos = pos;
 
-    let (opening_brace, next_pos) =
+    let (opening_brace, next_pos) = parse_token_type(tokens, current_pos, TokenType::LeftBrace)?;
-        match parse_token_type(tokens, current_pos, TokenType::LeftBrace) {
-            ParseResult::Ok(t, next) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
-            ParseResult::Mismatch(t) => return ParseResult::Mismatch(t),
-            ParseResult::Unmatched => return ParseResult::Unmatched,
-        };
     current_pos = next_pos;
 
     // Parse block statements
@@ -23,13 +17,12 @@ pub fn parse_block<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Block,
 
     // First statement
     match super::statement::try_parse(tokens, current_pos) {
-        ParseResult::Ok(statement, next_pos) => {
+        Ok((statement, next_pos)) => {
             current_pos = next_pos;
             statements.push(statement);
         }
-        ParseResult::Err(err) => return ParseResult::Err(err),
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-        ParseResult::Unmatched => {}
+        _ => {}
-        ParseResult::Mismatch(_) => {}
     }
 
     // More statements separated by new lines
@@ -40,11 +33,11 @@ pub fn parse_block<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Block,
         current_pos += 1;
 
         match super::statement::try_parse(tokens, current_pos) {
-            ParseResult::Ok(statement, next_pos) => {
+            Ok((statement, next_pos)) => {
                 current_pos = next_pos;
                 statements.push(statement);
             }
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
             _ => break,
         }
     }
@@ -52,26 +45,26 @@ pub fn parse_block<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Block,
     // Parse closing brace
     let (_closing_brace, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::RightBrace) {
-            ParseResult::Ok(t, next) => (t, next),
+            Ok((t, next)) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(t) => {
+            Err(ParsingError::Mismatch(t)) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing brace after the block body."),
                     error_start: t.position,
                     error_end: t.get_end_position(),
-                });
+                }));
             }
-            ParseResult::Unmatched => {
+            Err(ParsingError::Unmatched) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing brace after the block body."),
                     error_start: opening_brace.position,
                     error_end: opening_brace.get_end_position(),
-                });
+                }));
             }
         };
     current_pos = next_pos;
 
-    ParseResult::Ok(Block { statements }, current_pos)
+    Ok((Block { statements }, current_pos))
 }
 
 #[cfg(test)]
@@ -85,7 +78,7 @@ mod tests {
         let block = parse_block(&tokens, 0);
 
         let block = match block {
-            ParseResult::Ok(p, _) => p,
+            ParsingResult::Ok((p, _)) => p,
             _ => panic!("Expected a block, got: {:?}", block),
         };
 
@@ -98,7 +91,7 @@ mod tests {
         let block = parse_block(&tokens, 0);
 
         let block = match block {
-            ParseResult::Ok(p, _) => p,
+            ParsingResult::Ok((p, _)) => p,
             _ => panic!("Expected a block, got: {:?}", block),
         };
 
@@ -111,7 +104,7 @@ mod tests {
         let block = parse_block(&tokens, 0);
 
         let block = match block {
-            ParseResult::Ok(p, _) => p,
+            ParsingResult::Ok((p, _)) => p,
             _ => {
                 panic!("Expected a block, got: {:?}\n\n{:?}", block, tokens)
             }

src/syntax/expression/comparison.rs

@@ -1,6 +1,6 @@
 use crate::{
     lexic::token::Token,
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 /// Parses a factor expression.
@@ -8,20 +8,20 @@ use crate::{
 /// ```ebnf
 /// comparison = term, ((">" | ">=" | "<" | "<="), term)*;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let (term, next_pos) = match super::term::try_parse(tokens, pos) {
-        ParseResult::Ok(expr, next_pos) => (expr, next_pos),
+        Ok((expr, next_pos)) => (expr, next_pos),
-        _ => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
     };
 
     parse_many(tokens, next_pos, term)
 }
 
-fn parse_many(
+fn parse_many<'a>(
-    tokens: &Vec<Token>,
+    tokens: &'a Vec<Token>,
     pos: usize,
-    prev_expr: Expression,
+    prev_expr: Expression<'a>,
-) -> ParseResult<Expression, ()> {
+) -> ParsingResult<'a, Expression<'a>> {
     // comparison = term, ((">" | ">=" | "<" | "<="), term)*;
 
     match tokens.get(pos) {
@@ -32,18 +32,18 @@ fn parse_many(
                 || token.value == ">=" =>
         {
             match super::term::try_parse(tokens, pos + 1) {
-                ParseResult::Ok(expr, next_pos) => {
+                Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
                         Box::new(prev_expr),
                         Box::new(expr),
-                        Box::new(token.value.clone()),
+                        &token.value,
                     );
 
                     parse_many(tokens, next_pos, expr)
                 }
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             }
         }
-        _ => ParseResult::Ok(prev_expr, pos),
+        _ => Ok((prev_expr, pos)),
     }
 }

src/syntax/expression/equality.rs

@@ -1,6 +1,6 @@
 use crate::{
     lexic::token::Token,
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 /// Parses a factor expression.
@@ -8,37 +8,37 @@ use crate::{
 /// ```ebnf
 /// equality = comparison, (("==" | "!="), comparison )*;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let (comparison, next_pos) = match super::comparison::try_parse(tokens, pos) {
-        ParseResult::Ok(expr, next_pos) => (expr, next_pos),
+        Ok((expr, next_pos)) => (expr, next_pos),
-        _ => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
     };
 
     parse_many(tokens, next_pos, comparison)
 }
 
-fn parse_many(
+fn parse_many<'a>(
-    tokens: &Vec<Token>,
+    tokens: &'a Vec<Token>,
     pos: usize,
-    prev_expr: Expression,
+    prev_expr: Expression<'a>,
-) -> ParseResult<Expression, ()> {
+) -> ParsingResult<'a, Expression<'a>> {
     // equality = comparison, (("==" | "!="), comparison )*;
 
     match tokens.get(pos) {
         Some(token) if token.value == "==" || token.value == "!=" => {
             match super::comparison::try_parse(tokens, pos + 1) {
-                ParseResult::Ok(expr, next_pos) => {
+                Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
                         Box::new(prev_expr),
                         Box::new(expr),
-                        Box::new(token.value.clone()),
+                        &token.value,
                     );
 
                     parse_many(tokens, next_pos, expr)
                 }
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             }
         }
-        _ => ParseResult::Ok(prev_expr, pos),
+        _ => Ok((prev_expr, pos)),
     }
 }

src/syntax/expression/factor.rs

@@ -1,6 +1,6 @@
 use crate::{
     lexic::token::Token,
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 /// Parses a factor expression.
@@ -8,37 +8,37 @@ use crate::{
 /// ```ebnf
 /// factor = unary, (("/" | "*"), unary)*;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let (unary, next_pos) = match super::unary::try_parse(tokens, pos) {
-        ParseResult::Ok(expr, next_pos) => (expr, next_pos),
+        Ok((expr, next_pos)) => (expr, next_pos),
-        _ => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
     };
 
     parse_many(tokens, next_pos, unary)
 }
 
-fn parse_many(
+fn parse_many<'a>(
-    tokens: &Vec<Token>,
+    tokens: &'a Vec<Token>,
     pos: usize,
-    prev_expr: Expression,
+    prev_expr: Expression<'a>,
-) -> ParseResult<Expression, ()> {
+) -> ParsingResult<'a, Expression<'a>> {
     // (("/" | "*"), unary)*
 
     match tokens.get(pos) {
         Some(token) if token.value == "/" || token.value == "*" => {
             match super::unary::try_parse(tokens, pos + 1) {
-                ParseResult::Ok(expr, next_pos) => {
+                Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
                         Box::new(prev_expr),
                         Box::new(expr),
-                        Box::new(token.value.clone()),
+                        &token.value,
                     );
 
                     parse_many(tokens, next_pos, expr)
                 }
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             }
         }
-        _ => ParseResult::Ok(prev_expr, pos),
+        _ => Ok((prev_expr, pos)),
     }
 }

src/syntax/expression/function_call_expr.rs

@@ -3,7 +3,7 @@ use crate::{
     syntax::{
         ast::{functions::FunctionCall, Expression},
         functions::arguments_list,
-        ParseResult,
+        ParsingError, ParsingResult,
     },
 };
 
@@ -13,18 +13,18 @@ use crate::{
 /// function call expr = primary, "(", (arguments list)?, ")"
 ///                    | primary;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let (primary_expr, next_pos) = match super::primary::try_parse(tokens, pos) {
-        ParseResult::Ok(expr, next_pos) => (expr, next_pos),
+        Ok((expr, next_pos)) => (expr, next_pos),
-        _ => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
     };
 
     // Parse arguments list
     let (arguments, next_pos) = match arguments_list::try_parse(tokens, next_pos) {
-        ParseResult::Ok(args, next) => (args, next),
+        Ok((args, next)) => (args, next),
-        ParseResult::Err(err) => return ParseResult::Err(err),
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
         _ => {
-            return ParseResult::Ok(primary_expr, next_pos);
+            return Ok((primary_expr, next_pos));
         }
     };
 
@@ -33,7 +33,7 @@ pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()>
         arguments: Box::new(arguments),
     };
 
-    ParseResult::Ok(Expression::FunctionCall(fun_call), next_pos)
+    Ok((Expression::FunctionCall(fun_call), next_pos))
 }
 
 #[cfg(test)]

src/syntax/expression/mod.rs

@@ -1,4 +1,4 @@
-use super::{ast::Expression, ParseResult};
+use super::{ast::Expression, ParsingResult};
 use crate::lexic::token::Token;
 
 mod comparison;
@@ -10,8 +10,8 @@ mod term;
 mod unary;
 
 /// Expression is defined in the grammar.
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
-    return equality::try_parse(tokens, pos);
+    equality::try_parse(tokens, pos)
 }
 
 #[cfg(test)]

src/syntax/expression/primary.rs

@@ -1,7 +1,7 @@
 use super::super::utils::Tokenizer;
 use crate::{
     lexic::token::{Token, TokenType},
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 /// This grammar may not be up to date. Refer to the spec for the latest grammar.
@@ -9,42 +9,33 @@ use crate::{
 /// ```ebnf
 /// primary = number | string | boolean | identifier | ("(", expression, ")");
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     match tokens.get_significant(pos) {
         Some((token, token_pos)) => match token.token_type {
-            TokenType::Number => ParseResult::Ok(
+            TokenType::Number => Ok((Expression::Number(&token.value), token_pos + 1)),
-                Expression::Number(Box::new(token.value.clone())),
+            TokenType::String => Ok((Expression::String(&token.value), token_pos + 1)),
-                token_pos + 1,
-            ),
-            TokenType::String => ParseResult::Ok(
-                Expression::String(Box::new(token.value.clone())),
-                token_pos + 1,
-            ),
             TokenType::Identifier if token.value == "true" || token.value == "false" => {
-                ParseResult::Ok(Expression::Boolean(token.value == "true"), token_pos + 1)
+                Ok((Expression::Boolean(token.value == "true"), token_pos + 1))
             }
-            TokenType::Identifier => ParseResult::Ok(
+            TokenType::Identifier => Ok((Expression::Identifier(&token.value), token_pos + 1)),
-                Expression::Identifier(Box::new(token.value.clone())),
-                token_pos + 1,
-            ),
             TokenType::LeftParen => parse_parenthesized_expression(tokens, token_pos),
-            _ => ParseResult::Unmatched,
+            _ => Err(ParsingError::Unmatched),
         },
-        None => ParseResult::Unmatched,
+        None => Err(ParsingError::Unmatched),
     }
 }
 
-fn parse_parenthesized_expression(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+fn parse_parenthesized_expression(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let expression = super::try_parse(tokens, pos + 1);
     match expression {
-        ParseResult::Ok(expression, next_pos) => match tokens.get(next_pos) {
+        Ok((expression, next_pos)) => match tokens.get(next_pos) {
             Some(token) => match token.token_type {
-                TokenType::RightParen => ParseResult::Ok(expression, next_pos + 1),
+                TokenType::RightParen => Ok((expression, next_pos + 1)),
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             },
-            None => ParseResult::Unmatched,
+            None => Err(ParsingError::Unmatched),
         },
-        _ => ParseResult::Unmatched,
+        _ => Err(ParsingError::Unmatched),
     }
 }
 
@@ -59,7 +50,9 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::Number(value), _) => assert_eq!("40", format!("{}", value)),
+            Ok((Expression::Number(value), _)) => {
+                assert_eq!("40", format!("{}", value))
+            }
             _ => panic!(),
         }
     }
@@ -70,7 +63,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::String(value), _) => {
+            Ok((Expression::String(value), _)) => {
                 assert_eq!("\"Hello\"", format!("{}", value))
             }
             _ => panic!(),
@@ -83,7 +76,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::Boolean(value), _) => assert!(value),
+            Ok((Expression::Boolean(value), _)) => assert!(value),
             _ => panic!(),
         }
     }
@@ -94,7 +87,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::Identifier(value), _) => {
+            Ok((Expression::Identifier(value), _)) => {
                 assert_eq!("someIdentifier", format!("{}", value))
             }
             _ => panic!(),
@@ -107,7 +100,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::Identifier(value), _) => {
+            Ok((Expression::Identifier(value), _)) => {
                 assert_eq!("identifier", format!("{}", value))
             }
             _ => panic!(),

src/syntax/expression/term.rs

@@ -1,6 +1,6 @@
 use crate::{
     lexic::token::Token,
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 /// Parses a factor expression.
@@ -8,37 +8,37 @@ use crate::{
 /// ```ebnf
 /// term = factor, (("-" | "+"), factor)*;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     let (factor, next_pos) = match super::factor::try_parse(tokens, pos) {
-        ParseResult::Ok(expr, next_pos) => (expr, next_pos),
+        Ok((expr, next_pos)) => (expr, next_pos),
-        _ => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
     };
 
     parse_many(tokens, next_pos, factor)
 }
 
-fn parse_many(
+fn parse_many<'a>(
-    tokens: &Vec<Token>,
+    tokens: &'a Vec<Token>,
     pos: usize,
-    prev_expr: Expression,
+    prev_expr: Expression<'a>,
-) -> ParseResult<Expression, ()> {
+) -> ParsingResult<'a, Expression<'a>> {
     // term = factor, (("-" | "+"), factor)*;
 
     match tokens.get(pos) {
         Some(token) if token.value == "+" || token.value == "-" => {
             match super::factor::try_parse(tokens, pos + 1) {
-                ParseResult::Ok(expr, next_pos) => {
+                Ok((expr, next_pos)) => {
                     let expr = Expression::BinaryOperator(
                         Box::new(prev_expr),
                         Box::new(expr),
-                        Box::new(token.value.clone()),
+                        &token.value,
                     );
 
                     parse_many(tokens, next_pos, expr)
                 }
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             }
         }
-        _ => ParseResult::Ok(prev_expr, pos),
+        _ => Ok((prev_expr, pos)),
     }
 }

src/syntax/expression/unary.rs

@@ -1,6 +1,6 @@
 use crate::{
     lexic::token::Token,
-    syntax::{ast::Expression, ParseResult},
+    syntax::{ast::Expression, ParsingError, ParsingResult},
 };
 
 use super::function_call_expr;
@@ -11,15 +11,15 @@ use super::function_call_expr;
 /// unary = ("!" | "-"), expression
 ///       | function call expr;
 /// ```
-pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParseResult<Expression, ()> {
+pub fn try_parse(tokens: &Vec<Token>, pos: usize) -> ParsingResult<Expression> {
     match tokens.get(pos) {
         Some(token) if token.value == "!" || token.value == "-" => {
             match super::try_parse(tokens, pos + 1) {
-                ParseResult::Ok(expression, next_pos) => ParseResult::Ok(
+                Ok((expression, next_pos)) => Ok((
-                    Expression::UnaryOperator(Box::new(token.value.clone()), Box::new(expression)),
+                    Expression::UnaryOperator(&token.value, Box::new(expression)),
                     next_pos,
-                ),
+                )),
-                _ => ParseResult::Unmatched,
+                _ => Err(ParsingError::Unmatched),
             }
         }
         _ => function_call_expr::try_parse(tokens, pos),
@@ -37,7 +37,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::Identifier(value), _) => {
+            Ok((Expression::Identifier(value), _)) => {
                 assert_eq!("identifier", format!("{}", value))
             }
             _ => panic!(),
@@ -50,7 +50,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::UnaryOperator(operator, expression), _) => {
+            Ok((Expression::UnaryOperator(operator, expression), _)) => {
                 match (operator, *expression) {
                     (op, Expression::Number(value)) => {
                         assert_eq!(*op, "-");
@@ -69,7 +69,7 @@ mod tests {
         let expression = try_parse(&tokens, 0);
 
         match expression {
-            ParseResult::Ok(Expression::UnaryOperator(operator, expression), _) => {
+            Ok((Expression::UnaryOperator(operator, expression), _)) => {
                 assert_eq!(*operator, "-");
                 match *expression {
                     Expression::BinaryOperator(_, _, _) => {

src/syntax/functions/arguments_list.rs

@@ -4,19 +4,19 @@ use crate::{
     syntax::{
         ast::{functions::ArgumentsList, Expression},
         utils::parse_token_type,
-        ParseResult,
+        ParsingError, ParsingResult,
     },
 };
 
-pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<ArgumentsList, &Token> {
+pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<ArgumentsList> {
     let mut current_pos = pos;
 
     let (opening_paren, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::LeftParen) {
-            ParseResult::Ok(t, next) => (t, next),
+            Ok((t, next)) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(t) => return ParseResult::Mismatch(t),
+            Err(ParsingError::Mismatch(t)) => return Err(ParsingError::Mismatch(t)),
-            ParseResult::Unmatched => return ParseResult::Unmatched,
+            Err(ParsingError::Unmatched) => return Err(ParsingError::Unmatched),
         };
     current_pos = next_pos;
 
@@ -24,10 +24,10 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Argument
     loop {
         let (next_expression, next_pos) =
             match super::super::expression::try_parse(tokens, current_pos) {
-                ParseResult::Ok(expression, next_pos) => (expression, next_pos),
+                Ok((expression, next_pos)) => (expression, next_pos),
-                ParseResult::Err(error) => {
+                Err(ParsingError::Err(error)) => {
                     // TODO: Write a more detailed error
-                    return ParseResult::Err(error);
+                    return Err(ParsingError::Err(error));
                 }
                 _ => break,
             };
@@ -37,44 +37,44 @@ pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Argument
 
         // Parse comma. This also parses a trailing comma
         match parse_token_type(tokens, current_pos, TokenType::Comma) {
-            ParseResult::Ok(_, next) => {
+            Ok((_, next)) => {
                 current_pos = next;
             }
             // This should never happen
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(_) => {
+            Err(ParsingError::Mismatch(_)) => {
                 // Something other than a comma was found. It must be a closing paren )
                 // Still, break the loop, assume there are no more arguments
                 // TODO: This could be a good place to write a detailed error?
                 break;
             }
-            ParseResult::Unmatched => break,
+            Err(ParsingError::Unmatched) => break,
         };
     }
 
     // Parse closing paren
     let (_closing_paren, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::RightParen) {
-            ParseResult::Ok(t, next) => (t, next),
+            Ok((t, next)) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(t) => {
+            Err(ParsingError::Mismatch(t)) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing paren after the function identifier."),
                     error_start: t.position,
                     error_end: t.get_end_position(),
-                });
+                }));
             }
-            ParseResult::Unmatched => {
+            Err(ParsingError::Unmatched) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing paren after the function identifier."),
                     error_start: opening_paren.position,
                     error_end: opening_paren.get_end_position(),
-                });
+                }));
             }
         };
     current_pos = next_pos;
 
-    ParseResult::Ok(ArgumentsList { arguments }, current_pos)
+    Ok((ArgumentsList { arguments }, current_pos))
 }
 
 #[cfg(test)]
@@ -87,7 +87,7 @@ mod tests {
         let tokens = get_tokens(&String::from("()")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(list, next) = fun_decl else {
+        let Ok((list, next)) = fun_decl else {
             panic!("Expected an unmatched result: {:?}", fun_decl);
         };
 
@@ -100,7 +100,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(  )   ")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(list, next) = fun_decl else {
+        let Ok((list, next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 
@@ -113,7 +113,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(\n    \n)")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(list, next) = fun_decl else {
+        let Ok((list, next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 
@@ -126,7 +126,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(0)")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(arguments_list, next) = fun_decl else {
+        let Ok((arguments_list, next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 
@@ -145,7 +145,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(0, )")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(arguments_list, next) = fun_decl else {
+        let Ok((arguments_list, next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 
@@ -163,7 +163,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(\"Hello new world\", 322, )")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(arguments_list, _next) = fun_decl else {
+        let Ok((arguments_list, _next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 
@@ -185,7 +185,7 @@ mod tests {
         let tokens = get_tokens(&String::from("(foo(), bar())")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Ok(arguments_list, _next) = fun_decl else {
+        let Ok((arguments_list, _next)) = fun_decl else {
             panic!("Expected a result, got: {:?}", fun_decl);
         };
 

src/syntax/functions/function_declaration.rs

@@ -1,102 +1,96 @@
 use crate::{
     error_handling::SyntaxError,
     lexic::token::{Token, TokenType},
-    utils::Result3,
+    syntax::{ParsingError, ParsingResult},
 };
 
 use super::{
-    super::{
+    super::{ast::FunctionDeclaration, block::parse_block, utils::parse_token_type},
-        ast::FunctionDeclaration,
-        block::parse_block,
-        utils::{parse_token_type, try_token_type},
-        ParseResult,
-    },
     params_list::parse_params_list,
 };
 
-pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<FunctionDeclaration, ()> {
+pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<FunctionDeclaration> {
     let mut current_pos = pos;
 
     // `fun` keyword
-    let fun_keyword = match try_token_type(tokens, current_pos, TokenType::FUN) {
+    let (fun_keyword, next_pos) = match parse_token_type(tokens, current_pos, TokenType::FUN) {
-        Result3::Ok(t) => t,
+        Ok((t, next)) => (t, next),
-        Result3::Err(_token) => return ParseResult::Unmatched,
+        _ => return Err(ParsingError::Unmatched),
-        Result3::None => return ParseResult::Unmatched,
     };
-    current_pos += 1;
+    current_pos = next_pos;
 
     let (identifier, next_pos) = match parse_token_type(tokens, current_pos, TokenType::Identifier)
     {
-        ParseResult::Ok(id, next) => (id, next),
+        Ok((id, next)) => (id, next),
-        ParseResult::Err(err) => return ParseResult::Err(err),
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-        ParseResult::Mismatch(wrong_token) => {
+        Err(ParsingError::Mismatch(wrong_token)) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected an identifier after the `fun` keyword."),
                 error_start: wrong_token.position,
                 error_end: wrong_token.get_end_position(),
-            });
+            }));
         }
-        ParseResult::Unmatched => {
+        Err(ParsingError::Unmatched) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected an identifier after the `fun` keyword."),
                 error_start: fun_keyword.position,
                 error_end: fun_keyword.get_end_position(),
-            });
+            }));
         }
     };
     current_pos = next_pos;
 
     let (params_list, next_pos) = match parse_params_list(tokens, current_pos) {
-        ParseResult::Ok(params, next_pos) => (params, next_pos),
+        Ok((params, next_pos)) => (params, next_pos),
-        ParseResult::Err(err) => return ParseResult::Err(err),
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-        ParseResult::Mismatch(wrong_token) => {
+        Err(ParsingError::Mismatch(wrong_token)) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected an opening paren afted the function identifier."),
                 error_start: wrong_token.position,
                 error_end: wrong_token.get_end_position(),
-            });
+            }));
         }
-        ParseResult::Unmatched => {
+        Err(ParsingError::Unmatched) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected an opening paren afted the function identifier."),
                 error_start: identifier.position,
                 error_end: identifier.get_end_position(),
-            });
+            }));
         }
     };
     current_pos = next_pos;
 
     let (block, next_pos) = match parse_block(tokens, current_pos) {
-        ParseResult::Ok(block, next_pos) => (block, next_pos),
+        Ok((block, next_pos)) => (block, next_pos),
-        ParseResult::Err(error) => {
+        Err(ParsingError::Err(error)) => {
-            return ParseResult::Err(error);
+            return Err(ParsingError::Err(error));
         }
-        ParseResult::Mismatch(wrong_token) => {
+        Err(ParsingError::Mismatch(wrong_token)) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected a block after the function declaration."),
                 error_start: wrong_token.position,
                 error_end: wrong_token.get_end_position(),
-            });
+            }));
         }
-        ParseResult::Unmatched => {
+        Err(ParsingError::Unmatched) => {
-            return ParseResult::Err(SyntaxError {
+            return Err(ParsingError::Err(SyntaxError {
                 reason: String::from("Expected a block after the function declaration."),
                 error_start: identifier.position,
                 error_end: identifier.get_end_position(),
-            });
+            }));
         }
     };
     current_pos = next_pos;
 
     // Construct and return the function declaration
-    ParseResult::Ok(
+    Ok((
         FunctionDeclaration {
-            identifier: Box::new(identifier.value.clone()),
+            identifier: &identifier,
             params_list: Box::new(params_list),
             block: Box::new(block),
         },
         current_pos,
-    )
+    ))
 }
 
 #[cfg(test)]
@@ -110,7 +104,7 @@ mod tests {
         let tokens = get_tokens(&String::from("val identifier = 20")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
 
-        let ParseResult::Unmatched = fun_decl else {
+        let Err(ParsingError::Unmatched) = fun_decl else {
             panic!("Expected an unmatched result: {:?}", fun_decl);
         };
     }
@@ -121,7 +115,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an identifier after the `fun` keyword."
@@ -135,7 +129,7 @@ mod tests {
         let tokens = get_tokens(&String::from("fun")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an identifier after the `fun` keyword."
@@ -153,7 +147,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an opening paren afted the function identifier."
@@ -167,7 +161,7 @@ mod tests {
         let tokens = get_tokens(&String::from("fun id")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an opening paren afted the function identifier."
@@ -185,7 +179,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected a closing paren after the function identifier."
@@ -199,7 +193,7 @@ mod tests {
         let tokens = get_tokens(&String::from("fun id(")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected a closing paren after the function identifier."
@@ -217,7 +211,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an identifier after the `fun` keyword."
@@ -233,7 +227,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected an identifier after the `fun` keyword."
@@ -251,7 +245,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected a block after the function declaration."
@@ -265,7 +259,7 @@ mod tests {
         let tokens = get_tokens(&String::from("fun id()")).unwrap();
         let fun_decl = try_parse(&tokens, 0);
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(
                     err.reason,
                     "Expected a block after the function declaration."
@@ -283,7 +277,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(err.reason, "Expected a closing brace after the block body.");
                 assert_eq!(err.error_start, 11);
                 assert_eq!(err.error_end, 13);
@@ -295,7 +289,7 @@ mod tests {
         let fun_decl = try_parse(&tokens, 0);
 
         match fun_decl {
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
                 assert_eq!(err.reason, "Expected a closing brace after the block body.");
                 assert_eq!(err.error_start, 9);
                 assert_eq!(err.error_end, 10);
@@ -307,14 +301,9 @@ mod tests {
     #[test]
     fn should_parse_simple_function_declaration() {
         let tokens = get_tokens(&String::from("fun id() {}")).unwrap();
-        let ParseResult::Ok(function_declaration, _) = try_parse(&tokens, 0) else {
+        let (function_declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
-        };
 
-        assert_eq!(
+        assert_eq!(function_declaration.identifier.value, String::from("id"));
-            function_declaration.identifier,
-            Box::new(String::from("id"))
-        );
     }
 }
 
@@ -327,48 +316,38 @@ mod whitespace_test {
     #[test]
     fn should_ignore_whitespace_1() {
         let tokens = get_tokens(&String::from("fun\nid() {}")).unwrap();
-        let ParseResult::Ok(declaration, _) = try_parse(&tokens, 0) else {
+        let (declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
-        };
 
-        assert_eq!(declaration.identifier, Box::new(String::from("id")));
+        assert_eq!(declaration.identifier.value, (String::from("id")));
     }
 
     #[test]
     fn should_ignore_whitespace_2() {
         let tokens = get_tokens(&String::from("fun\nid\n() {}")).unwrap();
-        let ParseResult::Ok(declaration, _) = try_parse(&tokens, 0) else {
+        let (declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
-        };
 
-        assert_eq!(declaration.identifier, Box::new(String::from("id")));
+        assert_eq!(declaration.identifier.value, (String::from("id")));
     }
 
     #[test]
     fn should_ignore_whitespace_3() {
         let tokens = get_tokens(&String::from("fun\nid\n(\n) {}")).unwrap();
-        let ParseResult::Ok(declaration, _) = try_parse(&tokens, 0) else {
+        let (declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
-        };
 
-        assert_eq!(declaration.identifier, Box::new(String::from("id")));
+        assert_eq!(declaration.identifier.value, (String::from("id")));
     }
 
     #[test]
     fn should_ignore_whitespace_4() {
         let tokens = get_tokens(&String::from("fun id\n(\n)\n{}")).unwrap();
-        let ParseResult::Ok(declaration, _) = try_parse(&tokens, 0) else {
+        let (declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
+        assert_eq!(declaration.identifier.value, (String::from("id")));
-        };
-        assert_eq!(declaration.identifier, Box::new(String::from("id")));
     }
 
     #[test]
     fn should_ignore_whitespace_5() {
         let tokens = get_tokens(&String::from("fun\nid() \n{\n}")).unwrap();
-        let ParseResult::Ok(declaration, _) = try_parse(&tokens, 0) else {
+        let (declaration, _) = try_parse(&tokens, 0).unwrap();
-            panic!("Expected a function declaration.")
+        assert_eq!(declaration.identifier.value, (String::from("id")));
-        };
-        assert_eq!(declaration.identifier, Box::new(String::from("id")));
     }
 }

src/syntax/functions/params_list.rs

@@ -1,36 +1,41 @@
 use crate::{
     error_handling::SyntaxError,
     lexic::token::{Token, TokenType},
-    syntax::utils::parse_token_type,
+    syntax::{utils::parse_token_type, ParsingError, ParsingResult},
 };
 
 use super::super::{
     ast::{Parameter, ParamsList},
-    utils, ParseResult,
+    utils,
 };
 
-pub fn parse_params_list<'a>(
+pub fn parse_params_list<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<ParamsList> {
-    tokens: &'a Vec<Token>,
-    pos: usize,
-) -> ParseResult<ParamsList, &Token> {
     let mut current_pos = pos;
 
     let (opening_paren, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::LeftParen) {
-            ParseResult::Ok(t, next) => (t, next),
+            Ok((t, next)) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(t) => return ParseResult::Mismatch(t),
+            Err(ParsingError::Mismatch(t)) => return Err(ParsingError::Mismatch(&t)),
-            ParseResult::Unmatched => return ParseResult::Unmatched,
+            Err(ParsingError::Unmatched) => return Err(ParsingError::Unmatched),
         };
     current_pos = next_pos;
 
+    /*
+    val (opening_paren, next_pos) = try parse_token_type(...)
+
+    val (next_parameter, next_pos) = try parse_param_definition(...) catch
+    case ::Err(e) { return ::Err(e) }
+    else { break }
+     */
+
     // Parse parameters definitions, separated by commas
     let mut parameters = Vec::<Parameter>::new();
     loop {
         let (next_parameter, next_pos) = match parse_param_definition(tokens, current_pos) {
-            ParseResult::Ok(parameter, next_pos) => (parameter, next_pos),
+            Ok((parameter, next_pos)) => (parameter, next_pos),
-            ParseResult::Err(error) => {
+            Err(ParsingError::Err(error)) => {
-                return ParseResult::Err(error);
+                return Err(ParsingError::Err(error));
             }
             _ => break,
         };
@@ -39,50 +44,47 @@ pub fn parse_params_list<'a>(
 
         // Parse comma. This also parses a trailing comma
         match parse_token_type(tokens, current_pos, TokenType::Comma) {
-            ParseResult::Ok(_, next) => {
+            Ok((_, next)) => {
                 current_pos = next;
             }
             // This should never happen
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(_) => {
+            Err(ParsingError::Mismatch(_)) => {
                 // Something other than a comma was found. It must be a closing paren )
                 // Still, break the loop, assume there are no more arguments
                 // TODO: This could be a good place to write a detailed error?
                 break;
             }
-            ParseResult::Unmatched => break,
+            Err(ParsingError::Unmatched) => break,
         };
     }
 
     // Parse closing paren
     let (_closing_paren, next_pos) =
         match parse_token_type(tokens, current_pos, TokenType::RightParen) {
-            ParseResult::Ok(t, next) => (t, next),
+            Ok((t, next)) => (t, next),
-            ParseResult::Err(err) => return ParseResult::Err(err),
+            Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-            ParseResult::Mismatch(t) => {
+            Err(ParsingError::Mismatch(t)) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing paren after the function identifier."),
                     error_start: t.position,
                     error_end: t.get_end_position(),
-                });
+                }));
             }
-            ParseResult::Unmatched => {
+            Err(ParsingError::Unmatched) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected a closing paren after the function identifier."),
                     error_start: opening_paren.position,
                     error_end: opening_paren.get_end_position(),
-                });
+                }));
             }
         };
     current_pos = next_pos;
 
-    ParseResult::Ok(ParamsList {}, current_pos)
+    Ok((ParamsList {}, current_pos))
 }
 
-fn parse_param_definition<'a>(
+fn parse_param_definition<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Parameter> {
-    tokens: &'a Vec<Token>,
-    pos: usize,
-) -> ParseResult<Parameter, &Token> {
     // Parse a single parameter definition of the form:
     // - Type identifier
     // There will be more constructs in the future, like:
@@ -93,45 +95,45 @@ fn parse_param_definition<'a>(
     let mut current_pos = pos;
     let (datatype, next_pos) =
         match utils::parse_token_type(tokens, current_pos, TokenType::Datatype) {
-            ParseResult::Ok(token, next) => (token, next),
+            Ok((token, next)) => (token, next),
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
-                return ParseResult::Err(err);
+                return Err(ParsingError::Err(err));
             }
             // If there is no datatype this construction doesn't apply.
             // Return a mismatch and let the caller handle it
-            ParseResult::Mismatch(t) => return ParseResult::Mismatch(t),
+            Err(ParsingError::Mismatch(t)) => return Err(ParsingError::Mismatch(t)),
-            ParseResult::Unmatched => return ParseResult::Unmatched,
+            Err(ParsingError::Unmatched) => return Err(ParsingError::Unmatched),
         };
     current_pos = next_pos;
 
     let (identifier, next_pos) =
         match utils::parse_token_type(tokens, current_pos, TokenType::Identifier) {
-            ParseResult::Ok(token, next) => (token, next),
+            Ok((token, next)) => (token, next),
-            ParseResult::Err(err) => {
+            Err(ParsingError::Err(err)) => {
-                return ParseResult::Err(err);
+                return Err(ParsingError::Err(err));
             }
             // However, if we fail to parse an identifier, it's an error
-            ParseResult::Mismatch(_) => {
+            Err(ParsingError::Mismatch(_)) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected an identifier for the parameter."),
                     error_start: tokens[pos].position,
                     error_end: tokens[pos].get_end_position(),
-                });
+                }));
             }
-            ParseResult::Unmatched => {
+            Err(ParsingError::Unmatched) => {
-                return ParseResult::Err(SyntaxError {
+                return Err(ParsingError::Err(SyntaxError {
                     reason: String::from("Expected an identifier for the parameter."),
                     error_start: tokens[pos].position,
                     error_end: tokens[pos].get_end_position(),
-                })
+                }))
             }
         };
 
-    ParseResult::Ok(
+    Ok((
         Parameter {
-            identifier: Box::new(identifier.value.clone()),
+            identifier: &identifier.value,
-            datatype: Box::new(datatype.value.clone()),
+            datatype: &datatype.value,
         },
         next_pos,
-    )
+    ))
 }

src/syntax/grammar.md

@@ -1,19 +1,21 @@
 # Grammar
 
 
-## Module
+## Source file
-
-A module is (commonly) a single source file.
 
 ```ebnf
-module = top level declaration*
+source file = top level statement*
 ```
 
 
-## Top level declaration
+## Top level statement
+
+Current focus: Have a mvp compiler (w lexical/syntactic/semantic analysis + codegen) for
+simple function calls, and then implement other features top down
 
 ```ebnf
-top level declaration = function declaration
+top level statement = expression
+                    | function declaration
 ```
 
 

src/syntax/mod.rs

@@ -14,21 +14,19 @@ use ast::ModuleAST;
 
 use self::ast::TopLevelDeclaration;
 
+pub type ParsingResult<'a, A> = Result<(A, usize), ParsingError<'a>>;
+
 #[derive(Debug)]
-pub enum ParseResult<A, B> {
+pub enum ParsingError<'a> {
-    /// The parsing was a success. The first element is the parsed construct,
+    /// Some other token was found than the expected one
-    /// the second element is the position of the next token to parse
+    Mismatch(&'a Token),
-    Ok(A, usize),
+    /// The parsing didn't succeed, but it's not a fatal error
+    Unmatched,
     /// The parsing failed past a point of no return.
     ///
     /// For example, when parsing a function declaration
     /// the `fun` token is found, but then no identifier
     Err(SyntaxError),
-    /// Some special value was expected, but something else was found.
-    /// The inside element is the something else found.
-    Mismatch(B),
-    /// This parsing didn't succeed, but it's not a fatal error.
-    Unmatched,
 }
 
 /// Constructs the Misti AST from a vector of tokens
@@ -46,11 +44,11 @@ pub fn construct_ast<'a>(tokens: &'a Vec<Token>) -> Result<ModuleAST, MistiError
         }
 
         match next_construct(tokens, current_pos) {
-            ParseResult::Ok(module, next_pos) => {
+            Ok((module, next_pos)) => {
                 top_level_declarations.push(module);
                 current_pos = next_pos;
             }
-            ParseResult::Err(err) => return Err(MistiError::Syntax(err)),
+            Err(ParsingError::Err(err)) => return Err(MistiError::Syntax(err)),
             _ => {
                 return Err(MistiError::Syntax(SyntaxError {
                     reason: String::from("PARSER couldn't parse any construction"),
@@ -70,18 +68,21 @@ pub fn construct_ast<'a>(tokens: &'a Vec<Token>) -> Result<ModuleAST, MistiError
 fn next_construct<'a>(
     tokens: &'a Vec<Token>,
     current_pos: usize,
-) -> ParseResult<TopLevelDeclaration, ()> {
+) -> ParsingResult<TopLevelDeclaration> {
-    None.or_else(
+    // Try to parse a function declaration
-        || match functions::function_declaration::try_parse(tokens, current_pos) {
+    match functions::function_declaration::try_parse(tokens, current_pos) {
-            ParseResult::Ok(declaration, next_pos) => Some(ParseResult::Ok(
+        Ok((declaration, next_pos)) => {
+            return Ok((
                 TopLevelDeclaration::FunctionDeclaration(declaration),
                 next_pos,
-            )),
+            ))
-            ParseResult::Err(err) => Some(ParseResult::Err(err)),
+        }
-            _ => None,
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-        },
+        _ => {}
-    )
+    }
-    .unwrap_or_else(|| ParseResult::Unmatched)
+
+    // No top level construct was found, return unmatched
+    Err(ParsingError::Unmatched)
 }
 
 #[cfg(test)]
@@ -101,6 +102,7 @@ mod tests {
             TopLevelDeclaration::FunctionDeclaration(_f) => {
                 assert!(true)
             }
+            _ => panic!("Not implemented: Expression at top level"),
         }
     }
 
@@ -117,6 +119,7 @@ mod tests {
             TopLevelDeclaration::FunctionDeclaration(_f) => {
                 assert!(true)
             }
+            _ => panic!("Not implemented: Expression at top level"),
         }
 
         match declarations.get(1).unwrap() {
@@ -124,6 +127,7 @@ mod tests {
             TopLevelDeclaration::FunctionDeclaration(_f) => {
                 assert!(true)
             }
+            _ => panic!("Not implemented: Expression at top level"),
         }
     }
 }

src/syntax/statement.rs

@@ -4,26 +4,26 @@ use super::{
     ast::{statement::Statement, Expression},
     binding,
     expression::function_call_expr,
-    ParseResult,
+    ParsingError, ParsingResult,
 };
 
-pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParseResult<Statement, ()> {
+pub fn try_parse<'a>(tokens: &'a Vec<Token>, pos: usize) -> ParsingResult<Statement> {
-    None.or_else(|| match binding::try_parse(tokens, pos) {
+    // Try to parse a binding
-        ParseResult::Ok(b, next) => Some(ParseResult::Ok(Statement::Binding(b), next)),
+    match binding::try_parse(tokens, pos) {
-        ParseResult::Err(err) => Some(ParseResult::Err(err)),
+        Ok((b, next)) => return Ok((Statement::Binding(b), next)),
-        _ => None,
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
-    })
+        _ => {}
-    .or_else(|| match function_call_expr::try_parse(tokens, pos) {
-        ParseResult::Ok(f, next) => {
-            let Expression::FunctionCall(f) = f else {
-                return None;
-            };
-            Some(ParseResult::Ok(Statement::FunctionCall(f), next))
     }
-        ParseResult::Err(err) => Some(ParseResult::Err(err)),
+
-        _ => None,
+    // Try to parse a function call
-    })
+    match function_call_expr::try_parse(tokens, pos) {
-    .unwrap_or_else(|| ParseResult::Unmatched)
+        Ok((Expression::FunctionCall(f), next)) => return Ok((Statement::FunctionCall(f), next)),
+        Err(ParsingError::Err(err)) => return Err(ParsingError::Err(err)),
+        _ => {}
+    };
+
+    // Return unmatched
+    Err(ParsingError::Unmatched)
 }
 
 #[cfg(test)]
@@ -37,7 +37,7 @@ mod tests {
         let statement = try_parse(&tokens, 0);
 
         let statement = match statement {
-            ParseResult::Ok(s, _) => s,
+            Ok((s, _)) => s,
             _ => panic!("Expected a statement"),
         };
 
@@ -54,7 +54,7 @@ mod tests {
         let statement = try_parse(&tokens, 0);
 
         let statement = match statement {
-            ParseResult::Ok(s, _) => s,
+            Ok((s, _)) => s,
             _ => panic!("Expected a statement"),
         };
 

src/syntax/utils.rs

@@ -1,9 +1,6 @@
-use crate::{
+use crate::lexic::token::{Token, TokenType};
-    lexic::token::{Token, TokenType},
-    utils::Result3,
-};
 
-use super::ParseResult;
+use super::{ParsingError, ParsingResult};
 
 pub trait Tokenizer {
     fn get_significant<'a>(&'a self, index: usize) -> Option<(&'a Token, usize)>;
@@ -33,38 +30,31 @@ impl Tokenizer for Vec<Token> {
     }
 }
 
-/// Expects the token at `pos` to be of type `token_type`
+/// Expects the token at `pos` to be an operator of value `operator`. Doesn't ignore whitespace or newlines
-pub fn try_token_type(tokens: &Vec<Token>, pos: usize, token_type: TokenType) -> Result3<&Token> {
+pub fn try_operator(tokens: &Vec<Token>, pos: usize, operator: String) -> ParsingResult<&Token> {
     match tokens.get(pos) {
-        Some(t) if t.token_type == token_type => Result3::Ok(t),
+        Some(t) if t.token_type == TokenType::Operator && t.value == operator => Ok((t, pos + 1)),
-        Some(t) if t.token_type == TokenType::EOF || t.token_type == TokenType::NewLine => {
-            Result3::None
-        }
-        Some(t) => Result3::Err(t),
-        None => Result3::None,
-    }
-}
-
-pub fn try_operator(tokens: &Vec<Token>, pos: usize, operator: String) -> Result3<&Token> {
-    match tokens.get(pos) {
-        Some(t) if t.token_type == TokenType::Operator && t.value == operator => Result3::Ok(t),
         Some(t) if t.token_type == TokenType::NewLine || t.token_type == TokenType::EOF => {
-            Result3::None
+            Err(ParsingError::Unmatched)
         }
-        Some(t) => Result3::Err(t),
+        Some(t) => Err(ParsingError::Mismatch(t)),
-        None => Result3::None,
+        None => Err(ParsingError::Unmatched),
     }
 }
 
-/// Expects the token at `pos` to be of type `token_type`
+/// Expects the token at `pos` to be of type `token_type`, and returns the token and the next position.
+///
+/// Ignores all whitespace and newlines.
+///
+/// Only returns: Ok, Unmatched, Mismatched
 pub fn parse_token_type(
     tokens: &Vec<Token>,
     pos: usize,
     token_type: TokenType,
-) -> ParseResult<&Token, &Token> {
+) -> ParsingResult<&Token> {
     let mut current_pos = pos;
 
-    // Ignore all whitespace and newlines
+    // Ignore all whitespace, newlines and semicolons
     while let Some(t) = tokens.get(current_pos) {
         if t.token_type == TokenType::INDENT
             || t.token_type == TokenType::DEDENT
@@ -77,11 +67,11 @@ pub fn parse_token_type(
     }
 
     match tokens.get(current_pos) {
-        Some(t) if t.token_type == token_type => ParseResult::Ok(t, current_pos + 1),
+        Some(t) if t.token_type == token_type => Ok((t, current_pos + 1)),
         Some(t) if t.token_type == TokenType::EOF || t.token_type == TokenType::NewLine => {
-            ParseResult::Unmatched
+            Err(ParsingError::Unmatched)
         }
-        Some(t) => ParseResult::Mismatch(t),
+        Some(t) => Err(ParsingError::Mismatch(t)),
-        None => ParseResult::Unmatched,
+        None => Err(ParsingError::Unmatched),
     }
 }

src/utils/mod.rs

@@ -1,15 +0,0 @@
-pub enum Result3<T> {
-    Ok(T),
-    Err(T),
-    None,
-}
-
-#[allow(dead_code)]
-impl<T> Result3<T> {
-    pub fn unwrap(&self) -> &T {
-        match self {
-            Result3::Ok(t) => t,
-            _ => panic!(""),
-        }
-    }
-}