From 1fc116f2fee6e99318a284ceb0a7655d9e8242b4 Mon Sep 17 00:00:00 2001
From: Dustin Swan <dustin@dustinswan.com>
Date: Sun, 1 Feb 2026 00:18:43 -0700
Subject: [PATCH] parsing function application

---
 src/main.ts   |  2 +-
 src/parser.ts | 32 ++++++++++++++++++++++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/main.ts b/src/main.ts
index 5b875ad..66d3ac1 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -24,7 +24,7 @@ console.log(tokenize(str));
 // const tokens2 = tokenize("let x = (y) => 5 + y in x(3)");
 // const tokens2 = tokenize("let x = 5 in x * 4");
 // const tokens2 = tokenize("(x, y) => x + y");
-const tokens2 = tokenize('[1, 2, 3]');
+const tokens2 = tokenize('map double [1, 2, 3]');
 const p2 = new Parser(tokens2);
 const ast3 = p2.parse();
 console.log(ast3);
diff --git a/src/parser.ts b/src/parser.ts
index 932e756..bc955ef 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -52,17 +52,29 @@ export class Parser {
         }
     }
 
+    private canStartPrimary(): boolean {
+        const kind = this.current().kind;
+        return kind === 'ident' || kind === 'type-ident' ||
+            kind === 'int' || kind === 'float' || kind === 'string' ||
+            kind === 'open-paren' || kind === 'open-bracket' ||
+            kind === 'open-brace';
+    }
+
     parse(): AST {
         return this.parseExpression();
     }
 
     private parseExpression(): AST {
-        let left = this.parsePrimary();
+        return this.parseInfix();
+    }
+
+    private parseInfix(): AST {
+        let left = this.parseApplication();
 
         while (this.isInfixOp()) {
             const opToken = this.advance();
             const opName = this.tokenToOpName(opToken);
-            const right = this.parsePrimary();
+            const right = this.parseApplication();
 
             left = {
                 kind: 'apply',
@@ -74,6 +86,17 @@ export class Parser {
         return left;
     }
 
+    private parseApplication(): AST {
+        let func = this.parsePrimary();
+
+        while (this.canStartPrimary()) {
+            const arg = this.parsePrimary();
+            func = { kind: 'apply', func, args: [arg] };
+        }
+
+        return func;
+    }
+
     private parsePrimary(): AST {
         const token = this.current();
 
@@ -145,6 +168,11 @@ export class Parser {
             return { kind: 'variable', name: token.value };
         }
 
+        if (token.kind === 'type-ident') {
+            this.advance();
+            return { kind: 'constructor', name: token.value };
+        }
+
         throw new Error(`Unexpected token: ${token.kind}`);
     }