diff --git a/src/components/docs/CodeError.astro b/src/components/docs/CodeError.astro
index 6492ac4..3334ae9 100644
--- a/src/components/docs/CodeError.astro
+++ b/src/components/docs/CodeError.astro
@@ -4,5 +4,5 @@ const { error_type = "Unknown", error_message } = Astro.props;
 
 <div class="px-4 py-2 rounded bg-red-200 dark:bg-red-950">
     <span class="inline-block font-bold">{error_type} error:</span>
-    <span class="inline-block whitespace-pre-wrap">{error_message}</span>
+    <span class="whitespace-pre-wrap">{error_message}</span>
 </div>
diff --git a/src/lexer/highlighter.ts b/src/lexer/highlighter.ts
index 0eef368..2bb2e28 100644
--- a/src/lexer/highlighter.ts
+++ b/src/lexer/highlighter.ts
@@ -1,6 +1,12 @@
 import { spawn } from "node:child_process";
 import { leftTrimDedent } from "../components/utils";
 
+export type ReferenceItem = {
+    symbol_start: number
+    symbol_end: number
+    reference: string
+}
+
 export interface Token {
     token_type: TokenType
     value: string
@@ -55,13 +61,13 @@ export interface SemanticError {
 }
 
 export interface TokenizeResult {
-    Ok?: Token[],
+    Ok?: [Array<Token>, Array<ReferenceItem>],
     SyntaxOnly?: [Token[], Err],
     TokensOnly?: [Token[], Err],
     Err?: Err,
 }
 
-const error_classes = "underline decoration-wavy decoration-red-500";
+const error_classes = "underline underline-offset-4 decoration-wavy decoration-red-500";
 
 export async function native_highlighter(code: string): Promise<[string, string, string | null]> {
     let formatted_code = leftTrimDedent(code).join("\n");
@@ -85,7 +91,12 @@ export async function native_highlighter(code: string): Promise<[string, string,
         return semantic_error_highlighter(formatted_code, tokens, error.Semantic!);
     }
 
-    const tokens = result.Ok!;
+    const tokens = result.Ok! as unknown as Array<Token>;
+    // TODO: this is disable because the compiler has not
+    // implemented this feature yet
+    // const [tokens, references] = result.Ok!;
+    // console.log("refs:");
+    // console.log(references);
 
     const output = highlight_tokens(formatted_code, tokens);
 
@@ -107,22 +118,25 @@ function lex_error_highlighter(code: string, error: LexError): [string, string,
     const token = `<span class="token ${error_classes}">${err_str}</span>`;
 
     const all = `${before_err}${token}${after_err}`;
+    const [error_line, error_column] = absolute_to_line_column(code, error.position);
 
     // TODO: Transform absolute posijion (error.position) into line:column
-    return [all, "Lexical", error.reason + " at position " + error.position]
+    return [all, "Lexical", error.reason + ` at line ${error_line}:${error_column} `]
 }
 
 function syntax_error_highlighter(code: string, tokens: Array<Token>, error: SyntaxError): [string, string, string] {
     const highlighted = highlight_tokens(code, tokens, error.error_start, error.error_end);
+    const [error_line, error_column] = absolute_to_line_column(code, error.error_start);
 
-    const error_message = `${error.reason} from position ${error.error_start} to ${error.error_end}`;
+    const error_message = `${error.reason} at line ${error_line}:${error_column}`;
     return [highlighted, "Syntax", error_message];
 }
 
 function semantic_error_highlighter(code: string, tokens: Array<Token>, error: SyntaxError): [string, string, string] {
     const highlighted = highlight_tokens(code, tokens, error.error_start, error.error_end);
+    const [error_line, error_column] = absolute_to_line_column(code, error.error_start);
 
-    const error_message = `${error.reason} from position ${error.error_start} to ${error.error_end}`;
+    const error_message = `${error.reason} at line ${error_line}:${error_column}`;
     return [highlighted, "Semantic", error_message];
 }
 
@@ -149,7 +163,7 @@ function highlight_tokens(input: string, tokens: Array<Token>, error_start = -1,
         const token_start = t.position;
         const token_end = t.position + t.value.length;
 
-        let is_errored = (token_start == error_start);
+        let is_errored = (token_start >= error_start && token_end <= error_end);
 
         // Some tokens require processing (like multiline comments)
 
@@ -172,6 +186,33 @@ function highlight_tokens(input: string, tokens: Array<Token>, error_start = -1,
     return output;
 }
 
+/**
+ * Transform an absolute position in source code to a line:column combination.
+ * 
+ * Both line and column are 1-based
+ * 
+ * @param input the source code
+ * @param absolute the absolute position
+ */
+function absolute_to_line_column(input: string, absolute: number): [number, number] {
+    let line_count = 1;
+    let last_newline_pos = 0;
+
+    // Count lines
+    for (let i = 0; i < input.length; i += 1) {
+        if (i === absolute) {
+            break;
+        }
+
+        if (input[i] === "\n") {
+            line_count += 1;
+            last_newline_pos = i;
+        }
+    }
+
+    return [line_count, absolute - last_newline_pos];
+}
+
 /**
  * Certain tokens store values that differ from the source code representation.
  * For example, the multiline comment token stores the content of the comment
diff --git a/src/pages/learn/basics/datatypes.mdx b/src/pages/learn/basics/datatypes.mdx
index 403444e..6cef198 100644
--- a/src/pages/learn/basics/datatypes.mdx
+++ b/src/pages/learn/basics/datatypes.mdx
@@ -30,6 +30,9 @@ Int char_code = 0b01000110
 Int not_octal = 032     // This is 32, not 26
 `} />
 
+// TODO: Make it a compile error to have leading zeroes,
+and force users to use `0o` for octal
+
 
 ## Float
 
diff --git a/src/pages/learn/basics/operators.mdx b/src/pages/learn/basics/operators.mdx
index 5fc8cbb..32e47cf 100644
--- a/src/pages/learn/basics/operators.mdx
+++ b/src/pages/learn/basics/operators.mdx
@@ -27,7 +27,8 @@ number /= 1
 number %= 2
 `} />
 
-**There are no prefix/postfix increment**, use `+=` or `-=`.
+**There are no prefix/postfix increment operators** (`++`, `--`),
+use `+=` or `-=` instead.
 
 <Code thpcode={`
 // Use
diff --git a/src/pages/learn/functions/declaration.mdx b/src/pages/learn/functions/declaration.mdx
index 1cab1c6..f572365 100644
--- a/src/pages/learn/functions/declaration.mdx
+++ b/src/pages/learn/functions/declaration.mdx
@@ -64,9 +64,9 @@ val first = get_first_item(numbers)
 
 <Code thpcode={`
 () -> ()
-() -> Int
-(Int, Int) -> Int
-[T](Array[T]) -> T
+() -> (Int)
+(Int, Int) -> (Int)
+[T](Array[T]) -> (T)
 `} />
 
 
diff --git a/src/pages/learn/functions/higher-order.mdx b/src/pages/learn/functions/higher-order.mdx
index 790ac40..d24276f 100644
--- a/src/pages/learn/functions/higher-order.mdx
+++ b/src/pages/learn/functions/higher-order.mdx
@@ -10,7 +10,7 @@ import Code from "../../../components/Code.astro"
 ## Function as parameter
 
 <Code thpcode={`
-fun map[A, B](Array[A] input, (A) -> B function) -> Array[B]
+fun map[A, B](Array[A] input, (A) -> (B) function) -> Array[B]
 {
     // implementation
 }