start structs

README.md

@@ -0,0 +1,3 @@
+# a random language compiling to wasm
+
+The language is not well designed. It's just random garbage.

src/ast.ts

@@ -10,10 +10,15 @@ export type Identifier = {
 
 export type ItemId = number;
 
-export type ItemKind = {
+export type ItemKind =
+  | {
       kind: "function";
       node: FunctionDef;
-};
+    }
+  | {
+      kind: "type";
+      node: TypeDef;
+    };
 
 export type Item = ItemKind & {
   span: Span;
@@ -34,6 +39,17 @@ export type FunctionArg = {
   span: Span;
 };
 
+export type TypeDef = {
+  name: string;
+  fields: FieldDef[];
+  ty?: TyStruct;
+};
+
+export type FieldDef = {
+  name: Identifier;
+  type: Type;
+};
+
 export type ExprEmpty = { kind: "empty" };
 
 export type ExprLet = {
@@ -262,7 +278,21 @@ export type TyVar = {
   index: number;
 };
 
-export type Ty = TyString | TyInt | TyBool | TyList | TyTuple | TyFn | TyVar;
+export type TyStruct = {
+  kind: "struct";
+  name: string;
+  fields: [string, Ty][];
+};
+
+export type Ty =
+  | TyString
+  | TyInt
+  | TyBool
+  | TyList
+  | TyTuple
+  | TyFn
+  | TyVar
+  | TyStruct;
 
 export function tyIsUnit(ty: Ty): ty is TyUnit {
   return ty.kind === "tuple" && ty.elems.length === 0;
@@ -331,6 +361,19 @@ export function superFoldItem(item: Item, folder: Folder): Item {
         id: item.id,
       };
     }
+    case "type": {
+      const fields = item.node.fields.map(({ name, type }) => ({
+        name,
+        type: folder.type(type),
+      }));
+
+      return {
+        kind: "type",
+        span: item.span,
+        node: { name: item.node.name, fields },
+        id: item.id,
+      };
+    }
   }
 }
 

src/index.ts

@@ -10,8 +10,11 @@ import fs from "fs";
 import { exec } from "child_process";
 
 const input = `
-function main() = ();
+type Uwu = (
-function test(i: Int, j: Int): Bool = false == (i == 0);
+  meow: String,
+);
+
+function main(a: Int, b: Uwu) = ();
 `;
 
 function main() {
@@ -37,9 +40,10 @@ function main() {
     console.log(resolvedPrinted);
 
     console.log("-----AST typecked------");
-
     const typecked = typeck(resolved);
 
+    return;
+
     console.log("-----wasm--------------");
     const wasmModule = lowerToWasm(typecked);
     const moduleStringColor = writeModuleWatToString(wasmModule, true);

src/lexer.ts

@@ -7,6 +7,7 @@ export type DatalessToken =
   | "if"
   | "then"
   | "else"
+  | "type"
   | "("
   | ")"
   | "["
@@ -209,6 +210,7 @@ const keywords = new Set<string>([
   "if",
   "then",
   "else",
+  "type",
 ]);
 function isKeyword(kw: string): DatalessToken | undefined {
   return keywords.has(kw) ? (kw as DatalessToken) : undefined;

src/lower.ts

@@ -303,6 +303,8 @@ function computeAbi(ty: TyFn): Abi {
           return paramAbi(param.elems[0]);
         }
         todo("complex tuple abi");
+      case "struct":
+        todo("struct ABI");
       case "var":
         varUnreachable();
     }
@@ -333,6 +335,8 @@ function computeAbi(ty: TyFn): Abi {
         break;
       }
       todo("complex tuple abi");
+    case "struct":
+      todo("struct ABI");
     case "var":
       varUnreachable();
   }

src/parser.ts

@@ -5,16 +5,18 @@ import {
   BinaryKind,
   COMPARISON_KINDS,
   Expr,
+  FieldDef,
   FunctionArg,
   FunctionDef,
   Item,
   LOGICAL_KINDS,
   Type,
+  TypeDef,
   UNARY_KINDS,
   UnaryKind,
 } from "./ast";
 import { CompilerError, Span, todo } from "./error";
-import { BaseToken, Token, TokenIdent } from "./lexer";
+import { BaseToken, DatalessToken, Token, TokenIdent } from "./lexer";
 
 type Parser<T> = (t: Token[]) => [Token[], T];
 
@@ -41,24 +43,16 @@ function parseItem(t: Token[]): [Token[], Item] {
 
     [t] = expectNext(t, "(");
 
-    const args: FunctionArg[] = [];
+    let args: FunctionArg[];
-    let first = true;
+    [t, args] = parseCommaSeparatedList(t, ")", (t) => {
-    while (next(t)[1]?.kind !== ")") {
-      if (!first) {
-        [t] = expectNext(t, ",");
-      }
-      first = false;
-
       let name;
       [t, name] = expectNext<TokenIdent & { span: Span }>(t, "identifier");
       [t] = expectNext(t, ":");
       let type;
       [t, type] = parseType(t);
 
-      args.push({ name: name.ident, type, span: name.span });
+      return [t, { name: name.ident, type, span: name.span }];
-    }
+    });
-
-    [t] = expectNext(t, ")");
 
     let colon;
     let returnType = undefined;
@@ -91,6 +85,33 @@ function parseItem(t: Token[]): [Token[], Item] {
         id: 0,
       },
     ];
+  } else if (tok.kind === "type") {
+    let name;
+    [t, name] = expectNext<TokenIdent>(t, "identifier");
+    [t] = expectNext(t, "=");
+    [t] = expectNext(t, "(");
+
+    let fields;
+    [t, fields] = parseCommaSeparatedList<FieldDef>(t, ")", (t) => {
+      let name;
+      [t, name] = expectNext<TokenIdent>(t, "identifier");
+      [t] = expectNext(t, ":");
+      let type;
+      [t, type] = parseType(t);
+      return [t, { name: {
+        name: name.ident,
+        span: name.span,
+      }, type }];
+    });
+
+    [t] = expectNext(t, ";");
+
+    const def: TypeDef = {
+      name: name.ident,
+      fields,
+    };
+
+    return [t, { kind: "type", node: def, span: name.span, id: 0 }];
   } else {
     unexpectedToken(tok);
   }
@@ -125,7 +146,7 @@ function parseExpr(t: Token[]): [Token[], Expr] {
   if (peak.kind === "let") {
     [t] = expectNext(t, "let");
     let name;
-    [t, name] = expectNext<TokenIdent & Token>(t, "identifier");
+    [t, name] = expectNext<TokenIdent>(t, "identifier");
 
     let type = undefined;
     let colon;
@@ -236,15 +257,9 @@ function parseExprCall(t: Token[]): [Token[], Expr] {
   while (next(t)[1].kind === "(") {
     let popen;
     [t, popen] = next(t);
-    const args = [];
+
-    while (next(t)[1].kind !== ")") {
+    let args;
-      let arg;
+    [t, args] = parseCommaSeparatedList(t, ")", parseExpr);
-      [t, arg] = parseExpr(t);
-      args.push(arg);
-      // TODO i think this is incorrect
-      [t] = eat(t, ",");
-    }
-    [t] = expectNext(t, ")");
 
     lhs = { kind: "call", span: popen.span, lhs, args };
   }
@@ -331,20 +346,23 @@ function parseType(t: Token[]): [Token[], Type] {
       return [t, { kind: "list", elem, span }];
     }
     case "(": {
-      let first = true;
+      if (next(t)[1]?.kind === ")") {
-      const elems = [];
+        [t] = next(t);
-      while (next(t)[1]?.kind !== ")") {
+        return [t, { kind: "tuple", elems: [], span }];
-        if (!first) {
-          [t] = expectNext(t, ",");
       }
-        first = false;
+      let head;
-        let type;
+      [t, head] = parseType(t);
-        [t, type] = parseType(t);
-        elems.push(type);
-      }
-      [t] = expectNext(t, ")");
 
-      return [t, { kind: "tuple", elems, span }];
+      if (next(t)[1]?.kind === ")") {
+        [t] = next(t);
+        // Just a type inside parens, not a tuple. `(T,)` is a tuple.
+        return [t, head];
+      }
+
+      let tail;
+      [t, tail] = parseCommaSeparatedList(t, ")", parseType);
+
+      return [t, { kind: "tuple", elems: [head, ...tail], span }];
     }
     default: {
       throw new CompilerError(
@@ -357,6 +375,42 @@ function parseType(t: Token[]): [Token[], Type] {
 
 // helpers
 
+function parseCommaSeparatedList<R>(
+  t: Token[],
+  terminator: Token["kind"],
+  parser: Parser<R>
+): [Token[], R[]] {
+  const items: R[] = [];
+
+  // () | (a) | (a,) | (a, b)
+
+  while (true) {
+    if (next(t)[1]?.kind === terminator) {
+      break;
+    }
+
+    let nextValue;
+    [t, nextValue] = parser(t);
+
+    items.push(nextValue);
+
+    let comma;
+    [t, comma] = eat(t, ",");
+    if (!comma) {
+      // No comma? Fine, you don't like trailing commas.
+      // But this better be the end.
+      if (next(t)[1]?.kind !== terminator) {
+        unexpectedToken(next(t)[1]);
+      }
+      break;
+    }
+  }
+
+  [t] = expectNext(t, terminator);
+
+  return [t, items];
+}
+
 function eat<T extends BaseToken>(
   t: Token[],
   kind: T["kind"]
@@ -371,13 +425,13 @@ function eat<T extends BaseToken>(
 function expectNext<T extends BaseToken>(
   t: Token[],
   kind: T["kind"]
-): [Token[], T] {
+): [Token[], T & Token] {
   let tok;
   [t, tok] = next(t);
   if (tok.kind !== kind) {
     throw new CompilerError(`expected ${kind}, found ${tok.kind}`, tok.span);
   }
-  return [t, tok as unknown as T];
+  return [t, tok as unknown as T & Token];
 }
 
 function next(t: Token[]): [Token[], Token] {

src/printer.ts

@@ -7,6 +7,7 @@ import {
   Resolution,
   Ty,
   Type,
+  TypeDef,
   tyIsUnit,
 } from "./ast";
 
@@ -19,6 +20,9 @@ function printItem(item: Item): string {
     case "function": {
       return printFunction(item.node);
     }
+    case "type": {
+      return printTypeDef(item.node);
+    }
   }
 }
 
@@ -27,7 +31,18 @@ function printFunction(func: FunctionDef): string {
     .map(({ name, type }) => `${name}: ${printType(type)}`)
     .join(", ");
   const ret = func.returnType ? `: ${printType(func.returnType)}` : "";
-  return `function ${func.name}(${args})${ret} = ${printExpr(func.body, 0)}`;
+  return `function ${func.name}(${args})${ret} = ${printExpr(func.body, 0)};`;
+}
+
+function printTypeDef(type: TypeDef): string {
+  const fields = type.fields.map(
+    ({ name, type }) => `${ind(1)}${name.name}: ${printType(type)},`
+  );
+
+  const fieldPart =
+    type.fields.length === 0 ? "()" : `(\n${fields.join("\n")}\n)`;
+
+  return `type ${type.name} = ${fieldPart};`;
 }
 
 function printExpr(expr: Expr, indent: number): string {
@@ -165,6 +180,9 @@ export function printTy(ty: Ty): string {
     case "var": {
       return `?${ty.index}`;
     }
+    case "struct": {
+      return ty.name;
+    }
   }
 }
 

src/typeck.ts

@@ -20,6 +20,7 @@ import {
   TY_UNIT,
   TyFn,
   Type,
+  TyStruct,
 } from "./ast";
 import { CompilerError, Span } from "./error";
 import { printTy } from "./printer";
@@ -61,18 +62,7 @@ function lowerAstTyBase(
 ): Ty {
   switch (type.kind) {
     case "ident": {
-      const res = type.value.res!;
+      return lowerIdentTy(type.value);
-      switch (res.kind) {
-        case "local": {
-          throw new Error("Cannot resolve local here");
-        }
-        case "item": {
-          return typeOfItem(res.index);
-        }
-        case "builtin": {
-          return builtinAsTy(res.name, type.value.span);
-        }
-      }
     }
     case "list": {
       return {
@@ -112,6 +102,14 @@ export function typeck(ast: Ast): Ast {
 
         return { kind: "fn", params: args, returnTy };
       }
+      case "type": {
+        const fields = item.node.fields.map<[string, Ty]>(({ name, type }) => [
+          name.name,
+          lowerAstTy(type),
+        ]);
+
+        return { kind: "struct", name: item.node.name, fields };
+      }
     }
   }
 
@@ -122,7 +120,7 @@ export function typeck(ast: Ast): Ast {
         const res = ident.res!;
         switch (res.kind) {
           case "local": {
-            throw new Error("Cannot resolve local here");
+            throw new Error("Item type cannot refer to local variable");
           }
           case "item": {
             return typeOfItem(res.index);
@@ -149,7 +147,7 @@ export function typeck(ast: Ast): Ast {
             ty: fnTy.returnTy,
           };
           return {
-            kind: "function",
+            ...item,
             node: {
               name: item.node.name,
               params: item.node.params.map((arg, i) => ({
@@ -160,8 +158,34 @@ export function typeck(ast: Ast): Ast {
               returnType,
               ty: fnTy,
             },
-            span: item.span,
+          };
-            id: item.id,
+        }
+        case "type": {
+          const fieldNames = new Set();
+          item.node.fields.forEach(({ name }) => {
+            if (fieldNames.has(name)) {
+              throw new CompilerError(
+                `type ${item.node.name} has a duplicate field: ${name.name}`,
+                name.span
+              );
+            }
+            fieldNames.add(name);
+          });
+
+          const ty = typeOfItem(item.id) as TyStruct;
+
+          return {
+            ...item,
+            node: {
+              name: item.node.name,
+              fields: item.node.fields.map((field, i) => ({
+                name: field.name,
+                type: {
+                  ...field.type,
+                  ty: ty.fields[i][1],
+                },
+              })),
+            },
           };
         }
       }