struct literals

src/ast.ts

@@ -101,6 +101,12 @@ export type ExprIf = {
   else?: Expr;
 };
 
+export type ExprStructLiteral = {
+  kind: "structLiteral";
+  name: Identifier;
+  fields: [Identifier, Expr][];
+};
+
 export type ExprKind =
   | ExprEmpty
   | ExprLet
@@ -110,7 +116,8 @@ export type ExprKind =
   | ExprBinary
   | ExprUnary
   | ExprCall
-  | ExprIf;
+  | ExprIf
+  | ExprStructLiteral;
 
 export type Expr = ExprKind & {
   span: Span;
@@ -385,19 +392,19 @@ export function superFoldExpr(expr: Expr, folder: Folder): Expr {
     }
     case "let": {
       return {
+        ...expr,
         kind: "let",
         name: expr.name,
         type: expr.type && folder.type(expr.type),
         rhs: folder.expr(expr.rhs),
         after: folder.expr(expr.after),
-        span,
       };
     }
     case "block": {
       return {
+        ...expr,
         kind: "block",
         exprs: expr.exprs.map((expr) => folder.expr(expr)),
-        span,
       };
     }
     case "literal": {
@@ -408,36 +415,44 @@ export function superFoldExpr(expr: Expr, folder: Folder): Expr {
     }
     case "binary": {
       return {
+        ...expr,
         kind: "binary",
         binaryKind: expr.binaryKind,
         lhs: folder.expr(expr.lhs),
         rhs: folder.expr(expr.rhs),
-        span,
       };
     }
     case "unary": {
       return {
+        ...expr,
         kind: "unary",
         unaryKind: expr.unaryKind,
         rhs: folder.expr(expr.rhs),
-        span,
       };
     }
     case "call": {
       return {
+        ...expr,
         kind: "call",
         lhs: folder.expr(expr.lhs),
         args: expr.args.map((expr) => folder.expr(expr)),
-        span,
       };
     }
     case "if": {
       return {
+        ...expr,
         kind: "if",
         cond: folder.expr(expr.cond),
         then: folder.expr(expr.then),
         else: expr.else && folder.expr(expr.else),
-        span,
+      };
+    }
+    case "structLiteral": {
+      return {
+        ...expr,
+        kind: "structLiteral",
+        name: folder.ident(expr.name),
+        fields: expr.fields.map(([name, expr]) => [name, folder.expr(expr)]),
       };
     }
   }

src/index.ts

@@ -12,9 +12,12 @@ import { exec } from "child_process";
 const input = `
 type Uwu = (
   meow: String,
+  oops: Int,
+  aaa: (),
 );
 
-function main(a: Int, b: Uwu) = ();
+function aa(a: Int, b: Uwu): Uwu = Uwu {meow: "",oops:0,aaa:()};
+function main() = ();
 `;
 
 function main() {

src/lexer.ts

@@ -10,6 +10,8 @@ export type DatalessToken =
   | "type"
   | "("
   | ")"
+  | "{"
+  | "}"
   | "["
   | "]"
   | ";"
@@ -54,6 +56,8 @@ export type BaseToken = { kind: Token["kind"] };
 const SINGLE_PUNCT: string[] = [
   "(",
   ")",
+  "}",
+  "{",
   "[",
   "]",
   ";",

src/parser.ts

@@ -5,9 +5,11 @@ import {
   BinaryKind,
   COMPARISON_KINDS,
   Expr,
+  ExprStructLiteral,
   FieldDef,
   FunctionArg,
   FunctionDef,
+  Identifier,
   Item,
   LOGICAL_KINDS,
   Type,
@@ -98,10 +100,16 @@ function parseItem(t: Token[]): [Token[], Item] {
       [t] = expectNext(t, ":");
       let type;
       [t, type] = parseType(t);
-      return [t, { name: {
+      return [
+        t,
+        {
+          name: {
             name: name.ident,
             span: name.span,
-      }, type }];
+          },
+          type,
+        },
+      ];
     });
 
     [t] = expectNext(t, ";");
@@ -137,8 +145,9 @@ function parseExpr(t: Token[]): [Token[], Expr] {
 
   CALL = ATOM { "(" EXPR_LIST ")" }
 
-  ATOM = "(" { EXPR ";" } EXPR ")" | IDENT | LITERAL | EMPTY
+  ATOM = "(" { EXPR ";" } EXPR ")" | IDENT { STRUCT_INIT } | LITERAL | EMPTY
   EMPTY =
+  STRUCT_INIT = "{" { NAME ":" EXPR } { "," NAME ":" EXPR } { "," } "}"
   EXPR_LIST = { EXPR { "," EXPR } { "," } }
   */
   const [, peak] = next(t);
@@ -309,6 +318,22 @@ function parseExprAtom(startT: Token[]): [Token[], Expr] {
   }
 
   if (tok.kind === "identifier") {
+    console.log(t);
+
+    if (maybeNextT(t)[1]?.kind === "{") {
+      let fields;
+      [t, fields] = parseStructInit(t);
+      return [
+        t,
+        {
+          kind: "structLiteral",
+          name: { name: tok.ident, span },
+          fields,
+          span,
+        },
+      ];
+    }
+
     return [
       t,
       {
@@ -323,6 +348,23 @@ function parseExprAtom(startT: Token[]): [Token[], Expr] {
   return [startT, { kind: "empty", span }];
 }
 
+function parseStructInit(t: Token[]): [Token[], ExprStructLiteral["fields"]] {
+  [t] = expectNext(t, "{");
+
+  let fields;
+  [t, fields] = parseCommaSeparatedList<[Identifier, Expr]>(t, "}", (t) => {
+    let name;
+    [t, name] = expectNext<TokenIdent>(t, "identifier");
+    [t] = expectNext(t, ":");
+    let expr;
+    [t, expr] = parseExpr(t);
+
+    return [t, [{ name: name.ident, span: name.span }, expr]];
+  });
+
+  return [t, fields];
+}
+
 function parseType(t: Token[]): [Token[], Type] {
   let tok;
   [t, tok] = next(t);

src/printer.ts

@@ -126,6 +126,11 @@ function printExpr(expr: Expr, indent: number): string {
         indent + 1
       )}${elsePart}`;
     }
+    case "structLiteral": {
+      return `${printIdent(expr.name)} { ${expr.fields
+        .map(([name, expr]) => `${name.name}: ${printExpr(expr, indent + 1)}`)
+        .join(", ")} }`;
+    }
   }
 }
 

src/typeck.ts

@@ -84,15 +84,16 @@ function lowerAstTyBase(
 export function typeck(ast: Ast): Ast {
   const itemTys = new Map<number, Ty | null>();
   function typeOfItem(index: ItemId): Ty {
+    const item = ast.items[index];
+
     const ty = itemTys.get(index);
     if (ty) {
       return ty;
     }
     if (ty === null) {
-      throw Error(`cycle computing type of #G${index}`);
+      throw new CompilerError(`cycle computing type of #G${index}`, item.span);
     }
     itemTys.set(index, null);
-    const item = ast.items[index];
     switch (item.kind) {
       case "function": {
         const args = item.node.params.map((arg) => lowerAstTy(arg.type));
@@ -100,15 +101,28 @@ export function typeck(ast: Ast): Ast {
           ? lowerAstTy(item.node.returnType)
           : TY_UNIT;
 
-        return { kind: "fn", params: args, returnTy };
+        const ty: Ty = { kind: "fn", params: args, returnTy };
+        itemTys.set(item.id, ty);
+        return ty;
       }
       case "type": {
+        const ty: Ty = {
+          kind: "struct",
+          name: item.node.name,
+          fields: [
+            /*dummy*/
+          ],
+        };
+
+        itemTys.set(item.id, ty);
+
         const fields = item.node.fields.map<[string, Ty]>(({ name, type }) => [
           name.name,
           lowerAstTy(type),
         ]);
 
-        return { kind: "struct", name: item.node.name, fields };
+        ty.fields = fields;
+        return ty;
       }
     }
   }
@@ -379,6 +393,11 @@ export function checkBody(
         }
         break;
       }
+      case "struct": {
+        if (rhs.kind === "struct" && lhs.name === rhs.name) {
+          return;
+        }
+      }
     }
 
     throw new CompilerError(
@@ -516,6 +535,50 @@ export function checkBody(
 
           return { ...expr, cond, then, else: elsePart, ty };
         }
+        case "structLiteral": {
+          const fields = expr.fields.map<[Identifier, Expr]>(([name, expr]) => [
+            name,
+            this.expr(expr),
+          ]);
+
+          const structTy = typeOf(expr.name.res!, expr.name.span);
+
+          if (structTy.kind !== "struct") {
+            throw new CompilerError(
+              `struct literal is only allowed for struct types`,
+              expr.span
+            );
+          }
+
+          const assignedFields = new Set();
+
+          fields.forEach(([name, field], i) => {
+            const fieldTy = structTy.fields.find((def) => def[0] === name.name);
+            if (!fieldTy) {
+              throw new CompilerError(
+                `field ${name.name} doesn't exist on type ${expr.name.name}`,
+                name.span
+              );
+            }
+            assign(fieldTy[1], field.ty!, field.span);
+            assignedFields.add(name.name);
+          });
+
+          const missing: string[] = [];
+          structTy.fields.forEach(([name]) => {
+            if (!assignedFields.has(name)) {
+              missing.push(name);
+            }
+          });
+          if (missing.length > 0) {
+            throw new CompilerError(
+              `missing fields in literal: ${missing.join(", ")}`,
+              expr.span
+            );
+          }
+
+          return { ...expr, fields, ty: structTy };
+        }
       }
     },
   };