replace def = value with def: value, and let a = b with a = b

in the name of terseness

i'm also slipping in a new brush preset that i made

closes #125

crates/haku/src/compiler.rs

@@ -635,7 +635,7 @@ fn def_prepass<'a>(c: &mut Compiler<'a>, src: &Source<'a>, toplevel: NodeId) ->
     while let Some(binary) = walk.node_of(NodeKind::Binary) {
         let mut binary_walk = src.ast.walk(binary);
         if let (Some(ident), Some(op)) = (binary_walk.node(), binary_walk.get(NodeKind::Op)) {
-            if src.ast.span(op).slice(src.code) == "=" {
+            if src.ast.span(op).slice(src.code) == ":" {
                 let name = src.ast.span(ident).slice(src.code);
                 match c.defs.add_def(name) {
                     Ok(_) => (),
@@ -667,7 +667,7 @@ fn compile_toplevel_expr<'a>(
 ) -> CompileResult<ToplevelExpr> {
     if src.ast.kind(node_id) == NodeKind::Binary {
         if let Some(op) = src.ast.walk(node_id).get(NodeKind::Op) {
-            if src.ast.span(op).slice(src.code) == "=" {
+            if src.ast.span(op).slice(src.code) == ":" {
                 compile_def(c, src, node_id)?;
                 return Ok(ToplevelExpr::Def);
             }

crates/haku/src/lexer.rs

@@ -73,7 +73,6 @@ fn ident(l: &mut Lexer<'_>) -> TokenKind {
         "or" => TokenKind::Or,
         "if" => TokenKind::If,
         "else" => TokenKind::Else,
-        "let" => TokenKind::Let,
         _ => TokenKind::Ident,
     }
 }
@@ -210,6 +209,7 @@ fn token(l: &mut Lexer<'_>) -> (TokenKind, Span) {
         '[' => one(l, TokenKind::LBrack),
         ']' => one(l, TokenKind::RBrack),
         ',' => one(l, TokenKind::Comma),
+        ':' => one(l, TokenKind::Colon),
         '\\' => one(l, TokenKind::Backslash),
 
         _ => {

crates/haku/src/parser.rs

@@ -306,7 +306,7 @@ enum Tighter {
 fn tighter(left: TokenKind, right: TokenKind) -> Tighter {
     fn tightness(kind: TokenKind) -> Option<usize> {
         match kind {
-            TokenKind::Equal => Some(0),
+            TokenKind::Equal | TokenKind::Colon => Some(0),
             TokenKind::EqualEqual
             | TokenKind::NotEqual
             | TokenKind::Less
@@ -590,7 +590,6 @@ const PREFIX_TOKENS: TokenKindSet = TokenKindSet::new(&[
     TokenKind::LParen,
     TokenKind::Backslash,
     TokenKind::If,
-    TokenKind::Let,
     TokenKind::LBrack,
 ]);
 
@@ -606,7 +605,6 @@ fn prefix(p: &mut Parser) -> Closed {
         TokenKind::LParen => paren(p),
         TokenKind::Backslash => lambda(p),
         TokenKind::If => if_expr(p),
-        TokenKind::Let => let_expr(p),
 
         _ => {
             assert!(
@@ -637,7 +635,9 @@ fn infix(p: &mut Parser, op: TokenKind) -> NodeKind {
         | TokenKind::LessEqual
         | TokenKind::Greater
         | TokenKind::GreaterEqual
-        | TokenKind::Equal => infix_binary(p, op),
+        | TokenKind::Colon => infix_binary(p, op),
+
+        TokenKind::Equal => infix_let(p, op),
 
         _ if PREFIX_TOKENS.contains(op) => infix_call(p),
 
@@ -666,6 +666,31 @@ fn infix_call(p: &mut Parser) -> NodeKind {
     NodeKind::Call
 }
 
+fn infix_let(p: &mut Parser, op: TokenKind) -> NodeKind {
+    p.advance();
+
+    if p.peek() == TokenKind::Newline {
+        p.advance();
+    }
+
+    precedence_parse(p, op);
+
+    if p.peek() == TokenKind::Newline {
+        p.advance();
+    } else {
+        let span = p.span();
+        p.emit(Diagnostic::error(
+            span,
+            "new line expected after variable definition `a = b`",
+        ));
+        p.advance_with_error();
+    }
+
+    expr(p);
+
+    NodeKind::Let
+}
+
 pub fn expr(p: &mut Parser) {
     precedence_parse(p, TokenKind::Eof)
 }

crates/haku/src/parser/tests.rs

@@ -316,7 +316,7 @@ Binary @ 0..6
     );
 
     assert_ast_eq(
-        "1 = 1",
+        "1 : 1",
         expr,
         "
 Binary @ 0..5
@@ -864,52 +864,49 @@ Toplevel @ 1..63
 #[test]
 fn let_expr() {
     assert_ast_eq(
-        r#" let x = 1
+        r#" x = 1
             x "#,
         toplevel,
         "
-Toplevel @ 1..24
+Toplevel @ 1..20
-    Let @ 1..24
+    Let @ 1..20
-        Token @ 1..4
+        Ident @ 1..2
-        Ident @ 5..6
+            Token @ 1..2
+        Token @ 3..4
+        Number @ 5..6
             Token @ 5..6
-        Token @ 7..8
+        Token @ 6..7
-        Number @ 9..10
+        Ident @ 19..20
-            Token @ 9..10
+            Token @ 19..20",
-        Token @ 10..11
-        Ident @ 23..24
-            Token @ 23..24",
     );
 
     assert_ast_eq(
-        r#" let x = 1
+        r#" x = 1
-            let y = 2
+            y = 2
             x + y "#,
         toplevel,
         "
-Toplevel @ 1..50
+Toplevel @ 1..42
-    Let @ 1..50
+    Let @ 1..42
-        Token @ 1..4
+        Ident @ 1..2
-        Ident @ 5..6
+            Token @ 1..2
+        Token @ 3..4
+        Number @ 5..6
             Token @ 5..6
-        Token @ 7..8
+        Token @ 6..7
-        Number @ 9..10
+        Let @ 19..42
-            Token @ 9..10
+            Ident @ 19..20
-        Token @ 10..11
+                Token @ 19..20
-        Let @ 23..50
+            Token @ 21..22
-            Token @ 23..26
+            Number @ 23..24
-            Ident @ 27..28
+                Token @ 23..24
-                Token @ 27..28
+            Token @ 24..25
-            Token @ 29..30
+            Binary @ 37..42
-            Number @ 31..32
+                Ident @ 37..38
-                Token @ 31..32
+                    Token @ 37..38
-            Token @ 32..33
+                Op @ 39..40
-            Binary @ 45..50
+                    Token @ 39..40
-                Ident @ 45..46
+                Ident @ 41..42
-                    Token @ 45..46
+                    Token @ 41..42",
-                Op @ 47..48
-                    Token @ 47..48
-                Ident @ 49..50
-                    Token @ 49..50",
     )
 }

crates/haku/src/token.rs

@@ -34,6 +34,7 @@ pub enum TokenKind {
     RBrack,
     Comma,
     Equal,
+    Colon,
     Backslash,
     RArrow,
 
@@ -43,7 +44,6 @@ pub enum TokenKind {
     Or,
     If,
     Else,
-    Let,
 
     // NOTE: This must be kept last for TokenSet to work correctly.
     Error,