Multiple enhancements

- Make record expressions anonymous
 - Introduce `TNominal`
 - Add experimental support for type declarations (fixes #32)
 - Fix inference of StructDeclaration

src/checker.ts

@@ -1,4 +1,5 @@
 import {
+  Declaration,
   EnumDeclaration,
   EnumDeclarationStructElement,
   Expression,
@@ -25,6 +26,8 @@ import {
 import { assert, isEmpty, MultiMap } from "./util";
 import { Analyser } from "./analysis";
 
+// TODO check that the order by which kindArgs are inserted is correct
+
 const MAX_TYPE_ERROR_COUNT = 5;
 
 export enum TypeKind {
@@ -36,7 +39,7 @@ export enum TypeKind {
   Labeled,
   Record,
   App,
-  Variant,
+  Nominal,
 }
 
 abstract class TypeBase {
@@ -277,8 +280,6 @@ export class TRecord extends TypeBase {
   public readonly kind = TypeKind.Record;
 
   public constructor(
-    public decl: StructDeclaration | EnumDeclarationStructElement,
-    public kindArgs: TVar[],
     public fields: Map<string, Type>,
     public node: Syntax | null = null,
   ) {
@@ -293,8 +294,6 @@ export class TRecord extends TypeBase {
 
   public shallowClone(): TRecord {
     return new TRecord(
-      this.decl,
-      this.kindArgs,
       this.fields,
       this.node
     );
@@ -302,15 +301,6 @@ export class TRecord extends TypeBase {
 
   public substitute(sub: TVSub): Type {
     let changed = false;
-    const newTypeVars = [];
-    for (const typeVar of this.kindArgs) {
-      const newTypeVar = typeVar.substitute(sub);
-      assert(newTypeVar.kind === TypeKind.Var);
-      if (newTypeVar !== typeVar) {
-        changed = true;
-      }
-      newTypeVars.push(newTypeVar);
-    }
     const newFields = new Map();
     for (const [key, type] of this.fields) {
       const newType = type.substitute(sub);
@@ -319,7 +309,7 @@ export class TRecord extends TypeBase {
       }
       newFields.set(key, newType);
     }
-    return changed ? new TRecord(this.decl, newTypeVars, newFields, this.node) : this;
+    return changed ? new TRecord(newFields, this.node) : this;
   }
 
 }
@@ -336,12 +326,11 @@ export class TApp extends TypeBase {
     super(node);
   }
 
-  public static build(types: Type[], node: Syntax | null = null): Type {
+  public static build(resultType: Type, types: Type[], node: Syntax | null = null): Type {
-    let result = types[0];
+    for (let i = 0; i < types.length; i++) {
-    for (let i = 1; i < types.length; i++) {
+      resultType = new TApp(types[i], resultType, node);
-      result = new TApp(result, types[i], node);
     }
-    return result;
+    return resultType;
   }
 
   public *getTypeVars(): Iterable<TVar> {
@@ -372,54 +361,30 @@ export class TApp extends TypeBase {
 
 }
 
-export class TVariant extends TypeBase {
+export class TNominal extends TypeBase {
 
-  public readonly kind = TypeKind.Variant;
+  public readonly kind = TypeKind.Nominal;
 
   public constructor(
-    public decl: EnumDeclaration,
+    public decl: Declaration,
-    public kindArgs: Type[],
-    public elementTypes: Type[],
     public node: Syntax | null = null,
   ) {
     super(node);
   }
 
   public *getTypeVars(): Iterable<TVar> {
-    for (const elementType of this.elementTypes) {
+
-      yield* elementType.getTypeVars();
-    }
   }
 
   public shallowClone(): Type {
-    return new TVariant(
+    return new TNominal(
       this.decl,
-      this.kindArgs,
-      this.elementTypes,
       this.node,
     );
   }
 
   public substitute(sub: TVSub): Type {
-    let changed = false;
+    return this;
-    const newTypeVars = [];
-    for (const kindArg of this.kindArgs) {
-      const newTypeVar = kindArg.substitute(sub);
-      assert(newTypeVar.kind === TypeKind.Var);
-      if (newTypeVar !== kindArg) {
-        changed = true;
-      }
-      newTypeVars.push(newTypeVar);
-    }
-    const newElementTypes = [];
-    for (const elementType of this.elementTypes) {
-      const newElementType = elementType.substitute(sub);
-      if (newElementType !== elementType) {
-        changed = true;
-      }
-      newElementTypes.push(newElementType);
-    }
-    return changed ? new TVariant(this.decl, newTypeVars, newElementTypes, this.node) : this;
   }
 
 }
@@ -432,16 +397,7 @@ export type Type
   | TLabeled
   | TRecord
   | TApp
-  | TVariant
+  | TNominal
-
-type KindedType
-  = TRecord
-  | TVariant
-
-function isKindedType(type: Type): type is KindedType {
-  return type.kind === TypeKind.Variant
-      || type.kind === TypeKind.Record;
-}
 
 export const enum KindType {
   Star,
@@ -985,7 +941,21 @@ export class Checker {
       }
       case SyntaxKind.StructDeclaration:
       {
-        // TODO
+        const declKind = env.lookup(node.name.text)!;
+        const innerEnv = new KindEnv(env);
+        let kind: Kind = new KStar();
+        for (let i = node.varExps.length-1; i >= 0; i--) {
+          const varExpr = node.varExps[i];
+          const paramKind = this.createKindVar();
+          innerEnv.setNamed(varExpr.text, paramKind);
+          kind = new KArrow(paramKind, kind);
+        }
+        this.unifyKind(declKind, kind, node);
+        if (node.fields !== null) {
+          for (const field of node.fields) {
+            this.unifyKind(this.inferKindFromTypeExpression(field.typeExpr, innerEnv), new KStar(), field.typeExpr);
+          }
+        }
         break;
       }
       case SyntaxKind.EnumDeclaration:
@@ -1194,15 +1164,15 @@ export class Checker {
 
       case SyntaxKind.ReferenceExpression:
       {
-        assert(node.name.modulePath.length === 0);
+        assert(node.modulePath.length === 0);
         const scope = node.getScope();
-        const target = scope.lookup(node.name.name.text);
+        const target = scope.lookup(node.name.text);
         if (target !== null && target.kind === SyntaxKind.LetDeclaration && target.active) {
           return target.type!;
         }
-        const scheme = this.lookup(node.name.name.text, Symkind.Var);
+        const scheme = this.lookup(node.name.text, Symkind.Var);
         if (scheme === null) {
-          this.diagnostics.add(new BindingNotFoudDiagnostic(node.name.name.text, node.name.name));
+          this.diagnostics.add(new BindingNotFoudDiagnostic(node.name.text, node.name));
           return this.createTypeVar();
         }
         const type = this.instantiate(scheme, node);
@@ -1288,21 +1258,6 @@ export class Checker {
 
       case SyntaxKind.StructExpression:
       {
-        const scope = node.getScope();
-        const decl = scope.lookup(node.name.text, Symkind.Type);
-        if (decl === null) {
-          this.diagnostics.add(new BindingNotFoudDiagnostic(node.name.text, node.name));
-          return this.createTypeVar();
-        }
-        assert(decl.kind === SyntaxKind.StructDeclaration || decl.kind === SyntaxKind.EnumDeclarationStructElement);
-        const scheme = decl.scheme!;
-        const declType = this.instantiate(scheme, node);
-        const kindArgs = [];
-        const varExps = decl.kind === SyntaxKind.StructDeclaration
-          ? decl.varExps : (decl.parent! as EnumDeclaration).varExps;
-        for (const _ of varExps) {
-          kindArgs.push(this.createTypeVar());
-        }
         const fields = new Map();
         for (const member of node.members) {
           switch (member.kind) {
@@ -1328,19 +1283,7 @@ export class Checker {
               throw new Error(`Unexpected ${member}`);
           }
         }
-        let type: Type = TApp.build([ ...kindArgs, new TRecord(decl, [], fields, node) ]);
+        return new TRecord(fields, node);
-        if (decl.kind === SyntaxKind.EnumDeclarationStructElement) {
-          // TODO
-          // type = this.buildVariantType(decl, type);
-        }
-        this.addConstraint(
-          new CEqual(
-            declType,
-            type,
-            node,
-          )
-        );
-        return type;
       }
 
       case SyntaxKind.InfixExpression:
@@ -1409,10 +1352,10 @@ export class Checker {
 
       case SyntaxKind.AppTypeExpression:
       {
-        return TApp.build([
+        return TApp.build(
-          ...node.args.map(arg => this.inferTypeExpression(arg, introduceTypeVars)),
           this.inferTypeExpression(node.operator, introduceTypeVars),
-        ]);
+          node.args.map(arg => this.inferTypeExpression(arg, introduceTypeVars)),
+        );
       }
 
       case SyntaxKind.ArrowTypeExpression:
@@ -1550,7 +1493,7 @@ export class Checker {
           kindArgs.push(kindArg);
         }
         let elementTypes: Type[] = [];
-        const type = new TVariant(node, [], [], node);
+        const type = new TNominal(node, node);
         if (node.members !== null) {
           for (const member of node.members) {
             let elementType;
@@ -1558,14 +1501,22 @@ export class Checker {
               case SyntaxKind.EnumDeclarationTupleElement:
               {
                 const argTypes = member.elements.map(el => this.inferTypeExpression(el));
-                elementType = new TArrow(argTypes, TApp.build([ ...kindArgs, type ]));
+                elementType = new TArrow(argTypes, TApp.build(type, kindArgs));
-                parentEnv.add(member.name.text, new Forall(typeVars, constraints, elementType), Symkind.Var);
+                break;
+              }
+              case SyntaxKind.EnumDeclarationStructElement:
+              {
+                const fields = new Map();
+                for (const field of member.fields) {
+                  fields.set(field.name.text, this.inferTypeExpression(field.typeExpr));
+                }
+                elementType = new TArrow([ new TRecord(fields, member) ], TApp.build(type, kindArgs));
                 break;
               }
-              // TODO
               default:
                 throw new Error(`Unexpected ${member}`);
             }
+            parentEnv.add(member.name.text, new Forall(typeVars, constraints, elementType), Symkind.Var);
             elementTypes.push(elementType);
           }
         }
@@ -1586,14 +1537,17 @@ export class Checker {
           returnType: null,
         };
         this.pushContext(context);
+        const kindArgs = [];
         for (const varExpr of node.varExps) {
-          env.add(varExpr.text, new Forall([], [], this.createTypeVar()), Symkind.Type);
+          const typeVar = this.createTypeVar();
+          kindArgs.push(typeVar);
+          env.add(varExpr.text, new Forall([], [], typeVar), Symkind.Type);
         }
         const type = this.inferTypeExpression(node.typeExpression);
+        console.log(describeType(type));
         this.popContext(context);
-        const scheme = new Forall(typeVars, constraints, type);
+        const scheme = new Forall(typeVars, constraints, TApp.build(type, kindArgs));
         parentEnv.add(node.name.text, scheme, Symkind.Type); 
-        node.scheme = scheme;
         break;
       }
 
@@ -1616,20 +1570,21 @@ export class Checker {
           kindArgs.push(kindArg);
         }
         const fields = new Map<string, Type>();
-        if (node.members !== null) {
+        if (node.fields !== null) {
-          for (const member of node.members) {
+          for (const member of node.fields) {
             fields.set(member.name.text, this.inferTypeExpression(member.typeExpr));
           }
         }
         this.popContext(context);
-        const type = new TRecord(node, [], fields, node);
+        const type = new TNominal(node);
         parentEnv.add(node.name.text, new Forall(typeVars, constraints, type), Symkind.Type);
-        node.scheme = new Forall(typeVars, constraints, TApp.build([ ...kindArgs, type ]));
+        parentEnv.add(node.name.text, new Forall(typeVars, constraints, new TArrow([ new TRecord(fields, node) ], TApp.build(type, kindArgs))), Symkind.Var);
+        //node.scheme = new Forall(typeVars, constraints, );
         break;
       }
 
       default:
-        throw new Error(`Unexpected ${node}`);
+        throw new Error(`Unexpected ${node.constructor.name}`);
 
     }
 
@@ -1956,7 +1911,7 @@ export class Checker {
               return success;
             }
 
-            if (left.kind === TypeKind.Variant && right.kind === TypeKind.Variant) {
+            if (left.kind === TypeKind.Nominal && right.kind === TypeKind.Nominal) {
               if (left.decl !== right.decl) {
                 this.diagnostics.add(new UnificationFailedDiagnostic(left, right, [...constraint.getNodes()]));
                 return false;

src/cst.ts

@@ -1434,7 +1434,6 @@ export class StructExpression extends SyntaxBase {
   public readonly kind = SyntaxKind.StructExpression;
 
   public constructor(
-    public name: IdentifierAlt,
     public lbrace: LBrace,
     public members: StructExpressionElement[],
     public rbrace: RBrace,
@@ -1443,7 +1442,7 @@ export class StructExpression extends SyntaxBase {
   }
 
   public getFirstToken(): Token {
-    return this.name;
+    return this.lbrace;
   }
 
   public getLastToken(): Token {
@@ -1481,17 +1480,21 @@ export class ReferenceExpression extends SyntaxBase {
   public readonly kind = SyntaxKind.ReferenceExpression;
 
   public constructor(
-    public name: QualifiedName,
+    public modulePath: Array<[IdentifierAlt, Dot]>,
+    public name: Identifier | IdentifierAlt,
   ) {
     super();
   }
 
   public getFirstToken(): Token {
-    return this.name.getFirstToken();
+    if (this.modulePath.length > 0) {
+      return this.modulePath[0][0];
+    }
+    return this.name;
   }
 
   public getLastToken(): Token {
-     return this.name.getLastToken();
+     return this.name;
   }
 
 }
@@ -1718,7 +1721,7 @@ export class EnumDeclarationStructElement extends SyntaxBase {
   public constructor(
     public name: IdentifierAlt,
     public blockStart: BlockStart,
-    public members: StructDeclarationField[],
+    public fields: StructDeclarationField[],
   ) {
     super();
   }
@@ -1728,8 +1731,8 @@ export class EnumDeclarationStructElement extends SyntaxBase {
   }
 
   public getLastToken(): Token {
-    if (this.members.length > 0) {
+    if (this.fields.length > 0) {
-      return this.members[this.members.length-1].getLastToken();
+      return this.fields[this.fields.length-1].getLastToken();
     }
     return this.blockStart;
   }
@@ -1830,7 +1833,7 @@ export class StructDeclaration extends SyntaxBase {
     public structKeyword: StructKeyword,
     public name: IdentifierAlt,
     public varExps: Identifier[],
-    public members: StructDeclarationField[] | null,
+    public fields: StructDeclarationField[] | null,
   ) {
     super();
   }
@@ -1843,8 +1846,8 @@ export class StructDeclaration extends SyntaxBase {
   }
 
   public getLastToken(): Token {
-    if (this.members && this.members.length > 0) {
+    if (this.fields && this.fields.length > 0) {
-      return this.members[this.members.length-1].getLastToken();
+      return this.fields[this.fields.length-1].getLastToken();
     }
     return this.name;
   }

src/diagnostics.ts

@@ -1,5 +1,4 @@
 
-import { describe } from "yargs";
 import { TypeKind, type Type, type TArrow, TRecord, Kind, KindType } from "./checker";
 import { Syntax, SyntaxKind, TextFile, TextPosition, TextRange, Token } from "./cst";
 import { countDigits, IndentWriter } from "./util";
@@ -200,11 +199,21 @@ export function describeType(type: Type): string {
       }
       return out;
     }
-    case TypeKind.Variant:
+    case TypeKind.Nominal:
-    case TypeKind.Record:
     {
       return type.decl.name.text;
     }
+    case TypeKind.Record:
+    {
+      let out = '{ ';
+      let first = true;
+      for (const [fieldName, fieldType] of type.fields) {
+        if (first) first = false;
+        else out += ', ';
+        out += fieldName + ': ' + describeType(fieldType);
+      }
+      return out + ' }';
+    }
     case TypeKind.Labeled:
     {
       // FIXME may need to include fields that were added during unification

src/parser.ts

@@ -241,7 +241,7 @@ export class Parser {
     return new ConstantExpression(token);
   }
 
-  public parseQualifiedName(): QualifiedName {
+  public parseReferenceExpression(): ReferenceExpression {
     const modulePath: Array<[IdentifierAlt, Dot]> = [];
     for (;;) {
       const t0 = this.peekToken(1);
@@ -251,12 +251,11 @@ export class Parser {
       }
       modulePath.push([t0, t1]);
     }
-    const name = this.expectToken(SyntaxKind.Identifier);
+    const name = this.getToken();
-    return new QualifiedName(modulePath, name);
+    if (name.kind !== SyntaxKind.Identifier && name.kind !== SyntaxKind.IdentifierAlt) {
-  }
+      this.raiseParseError(name, [ SyntaxKind.Identifier, SyntaxKind.IdentifierAlt ]);
-
+    }
-  public parseReferenceExpression(): ReferenceExpression {
+    return new ReferenceExpression(modulePath, name);
-    return new ReferenceExpression(this.parseQualifiedName());
   }
 
   private parseExpressionWithParens(): Expression {
@@ -279,65 +278,47 @@ export class Parser {
       case SyntaxKind.LParen:
         return this.parseExpressionWithParens();
       case SyntaxKind.Identifier:
-        return this.parseReferenceExpression();
       case SyntaxKind.IdentifierAlt:
+        return this.parseReferenceExpression();
+      case SyntaxKind.LBrace:
       {
         this.getToken();
-        const t1 = this.peekToken();
+        const fields = [];
-        if (t1.kind === SyntaxKind.LBrace) {
+        let rbrace;
-          this.getToken();
-          const fields = [];
-          let rbrace;
-          for (;;) {
-            const t2 = this.peekToken();
-            if (t2.kind === SyntaxKind.RBrace) {
-              this.getToken();
-              rbrace = t2;
-              break;
-            }
-            let field;
-            const t3 = this.getToken();
-            if (t3.kind === SyntaxKind.Identifier) {
-              const t4 = this.peekToken();
-              if (t4.kind === SyntaxKind.Equals) {
-                this.getToken();
-                const expression = this.parseExpression();
-                field = new StructExpressionField(t3, t4, expression);
-              } else {
-                field = new PunnedStructExpressionField(t3);
-              }
-            } else {
-              // TODO add spread fields
-              this.raiseParseError(t3, [ SyntaxKind.Identifier ]);
-            }
-            fields.push(field);
-            const t5 = this.peekToken();
-            if (t5.kind === SyntaxKind.Comma) {
-              this.getToken();
-              continue;
-            } else if (t5.kind === SyntaxKind.RBrace) {
-              this.getToken();
-              rbrace = t5;
-              break;
-            }
-          }
-          return new StructExpression(t0, t1, fields, rbrace);
-        }
-        const elements = [];
         for (;;) {
           const t2 = this.peekToken();
-          if (t2.kind === SyntaxKind.LineFoldEnd
+          if (t2.kind === SyntaxKind.RBrace) {
-            || t2.kind === SyntaxKind.Comma
+            this.getToken();
-            || t2.kind === SyntaxKind.RParen
+            rbrace = t2;
-            || t2.kind === SyntaxKind.RBrace
+            break;
-            || t2.kind === SyntaxKind.RBracket
+          }
-            || isBinaryOperatorLike(t2)
+          let field;
-            || isPrefixOperatorLike(t2)) {
+          const t3 = this.getToken();
+          if (t3.kind === SyntaxKind.Identifier) {
+            const t4 = this.peekToken();
+            if (t4.kind === SyntaxKind.Equals) {
+              this.getToken();
+              const expression = this.parseExpression();
+              field = new StructExpressionField(t3, t4, expression);
+            } else {
+              field = new PunnedStructExpressionField(t3);
+            }
+          } else {
+            // TODO add spread fields
+            this.raiseParseError(t3, [ SyntaxKind.Identifier ]);
+          }
+          fields.push(field);
+          const t5 = this.peekToken();
+          if (t5.kind === SyntaxKind.Comma) {
+            this.getToken();
+            continue;
+          } else if (t5.kind === SyntaxKind.RBrace) {
+            this.getToken();
+            rbrace = t5;
             break;
           }
-          elements.push(this.parseExpression());
         }
-        return new NamedTupleExpression(t0, elements);
+        return new StructExpression(t0, fields, rbrace);
       }
       case SyntaxKind.Integer:
       case SyntaxKind.StringLiteral: