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Dustin Swan 2026-03-28 20:50:34 -06:00
parent 2b710602d3
commit 1f3a999092
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GPG key ID: 30D46587E2100467
2 changed files with 87 additions and 23 deletions
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4
src/cg/01-stdlib.cg
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@ -90,7 +90,7 @@ filter : (a \ Bool) \ List a \ List a = f list \ list
| True \ [x, ...filter f xs]
| False \ filter f xs);
insertAt : Int \ a \ List a = idx el list \ list
insertAt : Int \ a \ List a \ List a = idx el list \ list
| [] \ [el]
| [x, ...xs] \ (idx
| 0 \ [el, x, ...xs]
@ -196,7 +196,7 @@ range : Int \ Int \ List Int = start end \ start >= end
| False \ [start, ...range (start + 1) end];
# TODO Number
sum : List Int \ Int = list \ fold add 0 list;
sum : List a \ a = list \ fold add 0 list;
any : (a \ Bool) \ List a \ Bool = f list \ fold (acc x \ or acc (f x)) False list;

106
src/typechecker.ts
View file

@ -91,12 +91,22 @@ function infer(expr: AST, env: TypeEnv, subst: Subst): TypeAST | null {
case 'variable': {
const t = env.get(expr.name);
return t ? freshen(t, subst) : null;
if (!t) return null;
const { type: fresh } = freshen(t, subst);
// If this variable has a typeclass constraint, record it
const constraint = moduleConstraints.get(expr.name);
if (constraint && fresh.kind === 'type-function' && fresh.param.kind === 'type-var') {
inferredConstraints.push({ varName: fresh.param.name, className: constraint.className });
}
return fresh;
}
case 'constructor': {
const t = env.get(expr.name);
return t ? freshen(t, subst) : null;
if (!t) return null;
return freshen(t, subst).type;
}
case 'list': {
@ -148,7 +158,19 @@ function infer(expr: AST, env: TypeEnv, subst: Subst): TypeAST | null {
}
case 'apply': {
const funcType = infer(expr.func, env, subst);
let funcType: TypeAST | null = null;
let varMap: Map<string, string> | null = null;
if (expr.func.kind === 'variable') {
const t = env.get(expr.func.name);
if (t) {
const result = freshen(t, subst);
funcType = result.type;
varMap = result.varMap;
}
} else {
funcType = infer(expr.func, env, subst);
}
if (!funcType) return null;
let current = applySubst(funcType, subst);
@ -162,21 +184,22 @@ function infer(expr: AST, env: TypeEnv, subst: Subst): TypeAST | null {
// Check typeclass constraints
if (expr.func.kind === 'variable') {
const constraint = moduleConstraints.get(expr.func.name);
if (constraint) {
const argType = infer(expr.args[0], env, subst);
if (argType) {
const resolved = applySubst(argType, subst);
if (resolved.kind === 'type-name') {
const instances = moduleInstances.get(constraint.className);
if (!instances || !instances.has(resolved.name)) {
warn(`No instance ${constraint.className} ${resolved.name}`, expr);
}
} else if (resolved.kind === 'type-apply' && resolved.constructor.kind === 'type-name') {
const instances = moduleInstances.get(constraint.className);
if (!instances || !instances.has(resolved.constructor.name)) {
warn(`No instance ${constraint.className} ${resolved.constructor.name}`, expr);
}
if (constraint && varMap) {
const freshName = varMap.get(constraint.param) || constraint.param;
const resolved = applySubst({ kind: 'type-var', name: freshName }, subst);
if (resolved.kind === 'type-name') {
const instances = moduleInstances.get(constraint.className);
if (!instances || !instances.has(resolved.name)) {
warn(`No instance ${constraint.className} ${resolved.name}`, expr);
}
} else if (resolved.kind === 'type-apply' && resolved.constructor.kind === 'type-name') {
const instances = moduleInstances.get(constraint.className);
if (!instances || !instances.has(resolved.constructor.name)) {
warn(`No instance ${constraint.className} ${resolved.constructor.name}`, expr);
}
} else if (resolved.kind === 'type-var') {
inferredConstraints.push({ varName: resolved.name, className: constraint.className });
}
}
}
@ -291,7 +314,7 @@ function bindPattern(pattern: Pattern, type: TypeAST, env: TypeEnv, subst: Subst
// look up ctor types
const ctorType = env.get(pattern.name);
if (!ctorType) return null;
const fresh = freshen(ctorType, subst);
const fresh = freshen(ctorType, subst).type;
if (pattern.args.length === 0) {
unify(fresh, t, subst);
@ -325,7 +348,7 @@ function bindPattern(pattern: Pattern, type: TypeAST, env: TypeEnv, subst: Subst
return null;
}
if (t.kind === 'type-var') return null;
return `Connet match ${prettyPrintType(t)} against list pattern`;
return `Connot match ${prettyPrintType(t)} against list pattern`;
case 'record':
if (t.kind === 'type-record') {
for (const [key, pat] of Object.entries(pattern.fields)) {
@ -341,6 +364,7 @@ function bindPattern(pattern: Pattern, type: TypeAST, env: TypeEnv, subst: Subst
let moduleConstraints = new Map<string, { param: string, className: string }>();
let moduleInstances = new Map<string, Set<string>>();
let inferredConstraints: { varName: string, className: string }[] = [];
export function typecheck(defs: Definition[], typeDefs: TypeDefinition[] = [], classDefs: ClassDefinition[] = [], instances: InstanceDeclaration[] = []) {
const env: TypeEnv = new Map();
@ -391,6 +415,8 @@ export function typecheck(defs: Definition[], typeDefs: TypeDefinition[] = [], c
for (const def of defs) {
if (def.body) {
const subst: Subst = new Map();
inferredConstraints = []; // reset
if (def.annotation) {
const err = check(def.body, def.annotation.type, env, subst);
if (err) warn(err, def.body);
@ -398,6 +424,37 @@ export function typecheck(defs: Definition[], typeDefs: TypeDefinition[] = [], c
const t = infer(def.body, env, subst);
if (t) env.set(def.name, t);
}
// Propagate inferred constraints to this definition
if (inferredConstraints.length > 0 && def.annotation) {
// Collect annotation var names
const annoVars = new Set<string>();
function collectVars(t: TypeAST) {
if (t.kind === 'type-var') annoVars.add(t.name);
if (t.kind === 'type-function') { collectVars(t.param); collectVars(t.result); }
if (t.kind === 'type-apply') { collectVars(t.constructor); t.args.forEach(collectVars); }
if (t.kind === 'type-record') t.fields.forEach(f => collectVars(f.type));
}
collectVars(def.annotation.type);
for (const ic of inferredConstraints) {
// Walk subst chain to find which annotation var this connects to
let found: string | null = null;
for (const av of annoVars) {
const resolved = applySubst({ kind: 'type-var', name: av }, subst);
const icResolved = applySubst({ kind: 'type-var', name: ic.varName }, subst);
// If they resolve to the same thing, this annotation var is the one
if (unify(resolved, icResolved, new Map(subst)) === null) {
found = av;
break;
}
}
if (found) {
moduleConstraints.set(def.name, { param: found, className: ic.className });
}
}
}
}
}
}
@ -414,8 +471,9 @@ function occursIn(name: string, type: TypeAST, subst: Subst): boolean {
}
let freshCounter = 0;
function freshen(type: TypeAST, subst: Subst): TypeAST {
function freshen(type: TypeAST, subst: Subst): { type: TypeAST, varMap: Map<string, string> } {
const vars = new Map<string, TypeAST>();
function go(t: TypeAST): TypeAST {
const resolved = applySubst(t, subst);
switch (resolved.kind) {
@ -430,5 +488,11 @@ function freshen(type: TypeAST, subst: Subst): TypeAST {
case 'type-record': return { kind: 'type-record', fields: resolved.fields.map(f => ({ name: f.name, type: go(f.type) })) };
}
}
return go(type);
const result = go(type);
const varMap = new Map<string, string>();
for (const [old, fresh] of vars) {
if (fresh.kind === 'type-var') varMap.set(old, fresh.name);
}
return { type: result, varMap };
}