progress

util.js

@@ -1,3 +1,6 @@
+import { inspect } from 'node:util';
+import { symbolFunction, symbolList, symbolProduct, symbolSum } from './structures/types.js';
+
 // re-inventing the wheel:
 export function deepEqual(a, b) {
   if (a === b) return true; // <- shallow equality and primitives
@@ -45,17 +48,17 @@ export class DefaultMap {
   }
 }
 
-
-import { inspect } from 'node:util';
-import { symbolFunction, symbolList, symbolProduct, symbolSum } from './structures/types.js';
-
 export function pretty(obj) {
   return inspect(obj, {colors: true, depth: null});
 }
 
+// Pretty print type
 export function prettyT(type) {
   if (type.typeVars) {
-    return `∀${[...type.typeVars].map(prettyT).join(", ")}: ${prettyT(type.type)}`;
+    if (type.typeVars.size > 0) {
+      return `∀${[...type.typeVars].map(prettyT).join(", ")}: ${prettyT(type.type)}`;
+    }
+    return prettyT(type.type);
   }
   if (type.symbol === symbolFunction) {
     return `${prettyT(type.params[0])} -> ${prettyT(type.params[1])}`;