Separate enum & unions

src/lexer/identifier_lexer.ts

@@ -34,7 +34,7 @@ export function scan_identifier(input: string, starting_position: number, is_dat
 }
 
 function check_keyword(value: string): string {
-    const keywords = ["throws", "extends", "constructor", "case", "static", "const", "enum", "loop", "use", "break", "catch", "continue", "do", "else", "finally", "for", "fun", "if", "in", "fn", "nil", "return", "throw", "try", "while", "type", "match", "with", "of", "abstract", "class", "interface", "private", "pub", "override", "open", "init", "val", "var", "mut", "clone"];
+    const keywords = ["throws", "extends", "constructor", "case", "static", "const", "enum", "union", "loop", "use", "break", "catch", "continue", "do", "else", "finally", "for", "fun", "if", "in", "fn", "nil", "return", "throw", "try", "while", "type", "match", "with", "of", "abstract", "class", "interface", "private", "pub", "override", "open", "init", "val", "var", "mut", "clone"];
 
     if (keywords.includes(value)) {
         return "keyword";

src/pages/api/std/Array.mdx

@@ -141,6 +141,16 @@ abstraction, as if all indexes were valid.
 
 ## Usage
 
+### Empty array
+
+To create an empty array use square brackets.
+If you create an empty array, you need to specify the datatype.
+
+```thp
+Array[Int] empty = []
+```
+
+
 ### Creation
 
 To create an array use square brackets notation:
@@ -149,6 +159,8 @@ To create an array use square brackets notation:
 val numbers = [0, 1, 2, 3, 4, 5]
 ```
 
+When the array is not empty, you don't need to specify a datatype.
+
 When the Array is declared over many lines, the last
 item should have a trailing comma:
 

src/pages/api/std/Array/filter.md

@@ -0,0 +1,6 @@
+---
+layout: ../../../../layouts/ApiLayout.astro
+---
+
+# Array.filter
+

src/pages/learn/data-structures/enums.md

@@ -3,10 +3,18 @@ layout: ../../../layouts/DocsLayout.astro
 title: Enums
 ---
 
-# Enums (Tagged unions)
+# Enums
+
+From the [PHP documentation](https://www.php.net/manual/en/language.enumerations.overview.php):
+
+Enums allow a developer to define a custom type that is limited to one of a discrete number of possible values.
+
+THP enums are a 1 to 1 map of PHP enums, with a slightly different syntax.
 
 ## Basic enums
 
+Enums don't have a scalar value by default.
+
 ```thp
 enum Suit
 {
@@ -19,38 +27,21 @@ enum Suit
 val suit = Suit::Hearts
 ```
 
+## Backed enums
 
-## Enums with values
+Backed enums can have a scalar for each case. The scalar values can only be
+`String` or `Int`.
 
 ```thp
-enum IpAddress
+enum Suit(String)
 {
-    V4(String),
-    V6(String),
-}
-
-val addr_1 = IpAddress::V4("192.168.0.1")
-
-match addr_1
-case IpAddress::V4(ip)
-{
-    // code..
-}
-case IpAddress::V6(ip)
-{
-    // more code..
-}
-
-// Without the full qualifier
-match addr_1
-case ::V4(ip)
-{
-    // code...
-}
-case ::V6(ip)
-{
-    // even more code...
+    Hearts = "H",
+    Diamonds = "D",
+    Clubs = "C",
+    Spades = "S",
 }
 ```
 
+All cases must explicitly define their value, there is no automatic generation.
+
 

src/pages/learn/data-structures/unions.md

@@ -0,0 +1,58 @@
+---
+layout: ../../../layouts/DocsLayout.astro
+title: Tagged unions
+---
+
+# Tagged unions
+
+Tagged unions can hold a value from a fixed selection of types.
+
+```thp
+union Shape
+{
+    Dot,
+    Square(Int),
+    Rectangle(Int, Int),
+}
+
+val dot        = Shape::Dot
+val square1    = Shape::Square(10)
+val rectangle1 = Shape::Rectangle(5, 15)
+```
+
+## Pattern matching
+
+```thp
+match shape_1
+case ::Square(side)
+{
+    print("Area of the square: {side * side}")
+}
+case ::Rectangle(length, height)
+{
+    print("Area of the rectangle: {length * height}")
+}
+```
+
+## Internal representation
+
+When compiled down to PHP, tagged unions are a combination of an enum and an array.
+
+THP creates an enum of the same name and with the same cases, and the values
+are contained as part of an array.
+
+
+```php
+// The first snippet is compiled to:
+enum Shape
+{
+    case Dot;
+    case Square;
+    case Rectangle;
+}
+
+$dot        = [Shape::Dot];
+$square1    = [Shape::Square, 10];
+$rectangle1 = [Shape::Rectangle, 5, 15]
+```
+

src/pages/learn/index.mdx

@@ -26,6 +26,7 @@ pagesLayout:
   - path: arrays
   - path: maps
   - path: enums
+  - path: unions
 - path: functions
   title: Functions
   children:
@@ -59,7 +60,7 @@ THP is a new programming language that compiles to PHP.
 ![Accurate visual description of THP](/img/desc_thp.jpg)
 
 
-This page discusses some of the design decitions of the language,
+This page details the main design desitions of the language,
 if you want to install THP go to the [installation guide](install)
 
 
@@ -135,32 +136,41 @@ that it is a different language, and has different semantics.
 
 ## Some differences with PHP
 
-```thp
+```php
 // PHP
 $has_key = str_contains($haystack, 'needle');
+print("has key? " . $has_key);
+```
 
+```thp
 // THP
 val has_key = haystack.contains("needle")
+print("has key? " + has_key)
 ```
 
 - Explicit variable declaration
-- No `$` for variable names (and thus no `$$variable`)
+- No `$` for variable names (and thus no `$$variable`, use a map instead)
 - No semicolons
 - Use methods on common datatypes
 - Strings use only double quotes
+- String concatenation with `+`
 
----
 
-```thp
+<br/>
+<br/>
+
+```php
 // PHP
-[
+$obj = [
     'names' => ['Toni', 'Stark'],
     'age' => 33,
     'numbers' => [32, 64, 128]
 ]
+```
 
+```thp
 // THP
-.{
+val obj = .{
     names: #("Toni", "Stark"), // Tuple
     age: 33,
     numbers: [32, 64, 128]
@@ -170,29 +180,36 @@ val has_key = haystack.contains("needle")
 - Tuples, Arrays, Sets, Maps are clearly different
 - JSON-like object syntax
 
----
+<br/>
+<br/>
 
-```thp
+```php
 // PHP
 $cat = new Cat("Michifu", 7);
 $cat->meow();
+```
 
+
+```thp
 // THP
 val cat = Cat("Michifu", 7)
 cat.meow();
 ```
 
-- No `new` for classes
+- Instantiate classes without `new`
 - Use dot `.` instead of arrow `->` syntax
 
----
+<br/>
+<br/>
 
-
-```thp
+```php
 // PHP
 use \Some\Deeply\Nested\Class
 use \Some\Deeply\Nested\Interface
+```
 
+
+```thp
 // THP
 use Some::Deeply::Nested::{Class, Interface}
 ```
@@ -202,7 +219,9 @@ use Some::Deeply::Nested::{Class, Interface}
 - PSR-4 required
 - No `include`, `include_once`, `require` or `require_once`
 
----
+<br/>
+<br/>
+
 
 Other things:
 
@@ -232,8 +251,9 @@ val greeting =
     {
         "Nobody is here"
     }
+```
 
-
+```php
 // Would compile to:
 $greeting = null;
 $_person = get_person();
@@ -262,8 +282,9 @@ enum IpAddress {
 }
 
 val ip_1 = IpAddress::V4("255.255.0.0")
+```
 
-
+```php
 // Would possibly compile to:
 enum IpAddress {
     V4,

src/pages/spec/ast/ast.md

@@ -31,6 +31,33 @@ Statement = VariableBinding
 
 See the Expression section
 
-
+## VariableBinding
+
+```ebnf
+VariableBinding = ImplicitBinding
+                | ExplicitBinding
+
+ImplicitBinding = Datatype, Identifier, "=", Expression
+ExplicitBinding = ("var" | "val"), Datatype?, Identifier, "=", Expression
+```
+
+## FunctionDeclaration
+
+```ebnf
+FunctionDeclaration = "fun", Identifier, ParameterList, ("->", Datatype)?, Block
+
+ParameterList = "(", (Parameter, ",")*, ")"
+
+Parameter = Datatype, Identifier
+```
+
+## Block
+
+```ebnf
+Block       = "{", BlockMember*, "}"
+
+BlockMember = Statement
+            | Expression
+```