Implementing module system

Author: srad

demo/std/math.sml

@@ -0,0 +1,4 @@
+module Math
+
+val add = fun (a: _) -> fun (b: _) -> a + b;
+val sub = fun (a: _) -> fun (b: _) -> a - b;

demo/use_math.sml

@@ -0,0 +1,3 @@
+import "std/math.sml" as Math
+
+println ("3 + 4 = " ^ Math.add 3 4)

demo/use_math2.sml

@@ -0,0 +1,4 @@
+import "std/math.sml" as Math
+open Math
+
+println ("3 + 4 = " ^ add 3 4)

guess.js

@@ -0,0 +1,2 @@
+onlyBuiltDependencies:
+  - unrs-resolver

pnpm-lock.yaml

@@ -16,6 +16,7 @@ export type BinOp =
 
 export type STerm =
   | { t: "Var"; name: string }
+  | { t: "QVar"; mod: string; name: string }
   | { t: "Zero" }
   | { t: "Succ"; n: STerm }
   | { t: "Str"; value: string }
@@ -31,10 +32,24 @@ export type STerm =
 
 export type ADTCase = { ctor: string; binders: string[]; body: STerm };
 
+export type ImportDecl = {
+  d: "Import"; path: string; as?: string; open?: boolean;
+};
+
+export type ValDecl = {
+  d: "Val"; name: string; expr: STerm;
+};
+
 export type Decl =
-  | { d: "TypeDecl"; name: string; params: string[]; ctors: { name: string; fields: SType[] }[] };
+  | { d: "TypeDecl"; name: string; params: string[]; ctors: { name: string; fields: SType[] }[] }
+  | ImportDecl
+  | ValDecl;
 
-export type Program = { decls: Decl[]; main: STerm };
+export type Program = {
+  moduleName: string;     // filename or explicit `module Foo`
+  decls: Decl[];
+  main?: STerm;           // optional; default `unit`
+};
 
 // --- Core IR (unchanged) ---
 export type Term =
@@ -59,4 +74,9 @@ export const TSucc = (n: Term): Term => ({tag: "Succ", n});
 
 // --- Env ---
 export type ADT = { name: string; params: string[]; ctors: { name: string; fields: SType[] }[] };
-export type Env = { adts: Record<string, ADT>; vars: string[] };
+export type Env = {
+  adts: Record<string, ADT>;
+  vars: string[];                 // local lexical
+  globals: Record<string, true>;  // hoisted Val names
+  modules: Record<string, { vals: Record<string, true> }>;
+};