diff --git a/crates/codegen/src/ts.rs b/crates/codegen/src/ts.rs
index 0f82b2b..4378415 100644
--- a/crates/codegen/src/ts.rs
+++ b/crates/codegen/src/ts.rs
@@ -29,7 +29,7 @@ impl Codegen {
             self.emit(&self.gen_ir(&ir.kind, true));
         }
 
-        self.emit("f_main();");
+        self.emit("_main();");
     }
 
     fn gen_ir(&self, ir: &IRKind, should_gen_semicolon: bool) -> String {
@@ -39,7 +39,7 @@ impl Codegen {
         match ir {
             IRKind::Define { public, name, type_hint, value, mutable, .. } => {
                 format!(
-                    "{} {} v_{}: {} = {}{}\n",
+                    "{} {} _{}: {} = {}{}\n",
                     if *public { "export" } else { "" },
                     if *mutable { "let" } else { "const" },
                     name, 
@@ -51,7 +51,7 @@ impl Codegen {
 
             IRKind::Call { name, args, .. } => {
                 format!(
-                    "f_{}({}){}",
+                    "_{}({}){}",
                     name,
                     args
                         .iter()
@@ -82,11 +82,11 @@ impl Codegen {
             IRKind::Fun { public, name, return_type_hint, args, body, .. } => {
                 let args = args
                     .iter()
-                    .map(|arg| format!("v_{}: {}", arg.0, arg.1))
+                    .map(|arg| format!("_{}: {}", arg.0, arg.1))
                     .collect::<Vec<_>>().
                     join(", ");
                 format!(
-                    "{} const f_{} = ({}): {} => {};\n",
+                    "{} const _{} = ({}): {} => {};\n",
                     if *public { "export" } else { "" },
                     name,
                     args,
@@ -152,7 +152,7 @@ impl Codegen {
                     Value::Int(value)     => format!("{}", value),
                     Value::Boolean(value) => format!("{}", value),
                     Value::String(value)  => format!("\"{}\"", value),
-                    Value::Ident(value)   => format!("v_{}", value),
+                    Value::Ident(value)   => format!("_{}", value),
                 }
             },
 
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index e7cefe3..254da0d 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -455,13 +455,23 @@ fn gen_type_hint(type_hint: &Typehint) -> String {
             _ => t.to_string()
         },
         Typehint::Tuple(ts) => {
-            let mut types = Vec::new();
-            for t in ts {
-                types.push(gen_type_hint(&t.0));
-            }
+            let types = ts.iter().map(|arg| gen_type_hint(&arg.0)).collect::<Vec<_>>();
             format!("[{}]", types.join(", "))
         },
         Typehint::Vector(t) => format!("{}[]", gen_type_hint(&t.0)),
-        Typehint::Function(_args, _ret) => {dbg!(type_hint); todo!()}, // TODO: Function type
+        Typehint::Function(args, ret) => {
+            let args_ty = args.iter().map(|arg| gen_type_hint(&arg.0)).collect::<Vec<_>>();
+            let return_ty = gen_type_hint(&ret.0);
+            format!(
+                "({}) => {}",
+                args_ty
+                    .iter()
+                    .enumerate()
+                    .map(|(i, arg)| format!("__{}: {}", i, arg))
+                    .collect::<Vec<_>>()
+                    .join(", "),
+                return_ty
+            )
+        },
     }
 }
diff --git a/crates/parser/src/lib.rs b/crates/parser/src/lib.rs
index 54617f0..ba09b65 100644
--- a/crates/parser/src/lib.rs
+++ b/crates/parser/src/lib.rs
@@ -5,49 +5,51 @@ pub mod types;
 use types::{Expr, Spanned, Typehint};
 
 fn typehint_parser() -> impl Parser<Token, Spanned<Typehint>, Error = Simple<Token>> + Clone {
-    let single = filter_map(|span, token| match token {
-        Token::Identifier(s) => Ok((Typehint::Single(s), span)),
-        _ => Err(Simple::expected_input_found(span, Vec::new(), Some(token))),
-    });
-
-    let tuple = single
-        .separated_by(just(Token::Comma))
-        .allow_trailing()
-        .delimited_by(
-            just(Token::OpenParen),
-            just(Token::CloseParen),
-        )
-        .map_with_span(|args, span| {
-            (Typehint::Tuple(args), span)
+    recursive(|ty| {
+        let single = filter_map(|span, token| match token {
+            Token::Identifier(s) => Ok((Typehint::Single(s), span)),
+            _ => Err(Simple::expected_input_found(span, Vec::new(), Some(token))),
         });
 
-    let vector = single
-        .delimited_by(
-            just(Token::OpenBracket),
-            just(Token::CloseBracket),
-        )
-        .map_with_span(|arg, span| {
-            (Typehint::Vector(Box::new(arg)), span)
-        });
+        let tuple = single
+            .separated_by(just(Token::Comma))
+            .allow_trailing()
+            .delimited_by(
+                just(Token::OpenParen),
+                just(Token::CloseParen),
+            )
+            .map_with_span(|args, span| {
+                (Typehint::Tuple(args), span)
+            });
 
-    let function = single
-        .separated_by(just(Token::Comma))
-        .allow_trailing()
-        .delimited_by(
-            just(Token::Pipe),
-            just(Token::Pipe),
-        )
-        .then_ignore(just(Token::Arrow))
-        .then(single)
-        .map_with_span(|(args, ret), span| {
-            (Typehint::Function(args, Box::new(ret)), span)
-        });
+        let vector = single
+            .delimited_by(
+                just(Token::OpenBracket),
+                just(Token::CloseBracket),
+            )
+            .map_with_span(|arg, span| {
+                (Typehint::Vector(Box::new(arg)), span)
+            });
 
-    single
-        .or(tuple)
-        .or(vector)
-        .or(function)
-        .labelled("type hint")
+        let function = ty
+            .separated_by(just(Token::Comma))
+            .allow_trailing()
+            .delimited_by(
+                just(Token::Pipe),
+                just(Token::Pipe),
+            )
+            .then_ignore(just(Token::Arrow))
+            .then(single)
+            .map_with_span(|(args, ret), span| {
+                (Typehint::Function(args, Box::new(ret)), span)
+            });
+
+        single
+            .or(tuple)
+            .or(vector)
+            .or(function)
+            .labelled("type hint")
+    })
 }
 
 fn expr_parser() -> impl Parser<Token, Vec<Spanned<Expr>>, Error = Simple<Token>> + Clone {
diff --git a/example/tuples.hz b/example/tuples.hz
index cba831f..016f342 100644
--- a/example/tuples.hz
+++ b/example/tuples.hz
@@ -1,6 +1,14 @@
-fun test (foo: int) (bar: int) : int = foo * bar
-fun f (fn: |int, int| -> int) (x: int) : int = fn(x)
+fun mul (foo: int) (bar: int) : int = foo * bar
+fun map
+    (fn: |int, int| -> int)
+    (to: int)
+    : int
+= fn(to, 10)
 
 fun main: void = do
-    let x : int = 20
-end
\ No newline at end of file
+    let foo : int = 69
+    let bar : int = 10
+
+    map(mul, foo)
+    |> @write(_)
+end