diff --git a/package-lock.json b/package-lock.json
index b43ea1d..20480cb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -601,9 +601,9 @@
       }
     },
     "node_modules/@fink/loxia": {
-      "version": "18.1.0",
-      "resolved": "https://registry.npmjs.org/@fink/loxia/-/loxia-18.1.0.tgz",
-      "integrity": "sha512-z0EOPuwGo8ceSOFZhYf3HD/sBFzFD2tMhVXJ9HeSiLf2OI/EAH7e8fPyN08GYU41yEdzKP54kNi5LG3P9aYbBw==",
+      "version": "18.2.0",
+      "resolved": "https://registry.npmjs.org/@fink/loxia/-/loxia-18.2.0.tgz",
+      "integrity": "sha512-MGdfJwGFOtUqbs23/TMqS6PLWjPdo9P0hIcCZ1E2bkS/r6GKCrIBR8+ytq5cngTVkWbw2u3Nd7Qc4trLKBA0Iw==",
       "dev": true,
       "dependencies": {
         "@babel/core": "^7.10.5",
@@ -4433,9 +4433,9 @@
       "dev": true
     },
     "node_modules/fsevents": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.2.0.tgz",
-      "integrity": "sha512-pKnaUh2TNvk+/egJdBw1h46LwyLx8BzEq+MGCf/RMCVfEHHsGOCWG00dqk91kUPPArIIwMBg9T/virxwzP03cA==",
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.2.1.tgz",
+      "integrity": "sha512-bTLYHSeC0UH/EFXS9KqWnXuOl/wHK5Z/d+ghd5AsFMYN7wIGkUCOJyzy88+wJKkZPGON8u4Z9f6U4FdgURE9qA==",
       "dev": true,
       "hasInstallScript": true,
       "optional": true,
@@ -17372,7 +17372,6 @@
       "resolved": "https://registry.npmjs.org/uuid/-/uuid-8.3.1.tgz",
       "integrity": "sha512-FOmRr+FmWEIG8uhZv6C2bTgEVXsHk08kE7mPlrBbEe+c3r9pjceVPgupIfNIhc4yx55H69OXANrUaSuu9eInKg==",
       "dev": true,
-      "optional": true,
       "bin": {
         "uuid": "dist/bin/uuid"
       }
@@ -18382,9 +18381,9 @@
       }
     },
     "@fink/loxia": {
-      "version": "18.1.0",
-      "resolved": "https://registry.npmjs.org/@fink/loxia/-/loxia-18.1.0.tgz",
-      "integrity": "sha512-z0EOPuwGo8ceSOFZhYf3HD/sBFzFD2tMhVXJ9HeSiLf2OI/EAH7e8fPyN08GYU41yEdzKP54kNi5LG3P9aYbBw==",
+      "version": "18.2.0",
+      "resolved": "https://registry.npmjs.org/@fink/loxia/-/loxia-18.2.0.tgz",
+      "integrity": "sha512-MGdfJwGFOtUqbs23/TMqS6PLWjPdo9P0hIcCZ1E2bkS/r6GKCrIBR8+ytq5cngTVkWbw2u3Nd7Qc4trLKBA0Iw==",
       "dev": true,
       "requires": {
         "@babel/core": "^7.10.5",
@@ -21451,9 +21450,9 @@
       "dev": true
     },
     "fsevents": {
-      "version": "2.2.0",
-      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.2.0.tgz",
-      "integrity": "sha512-pKnaUh2TNvk+/egJdBw1h46LwyLx8BzEq+MGCf/RMCVfEHHsGOCWG00dqk91kUPPArIIwMBg9T/virxwzP03cA==",
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.2.1.tgz",
+      "integrity": "sha512-bTLYHSeC0UH/EFXS9KqWnXuOl/wHK5Z/d+ghd5AsFMYN7wIGkUCOJyzy88+wJKkZPGON8u4Z9f6U4FdgURE9qA==",
       "dev": true,
       "optional": true
     },
@@ -31604,8 +31603,7 @@
       "version": "8.3.1",
       "resolved": "https://registry.npmjs.org/uuid/-/uuid-8.3.1.tgz",
       "integrity": "sha512-FOmRr+FmWEIG8uhZv6C2bTgEVXsHk08kE7mPlrBbEe+c3r9pjceVPgupIfNIhc4yx55H69OXANrUaSuu9eInKg==",
-      "dev": true,
-      "optional": true
+      "dev": true
     },
     "v8-to-istanbul": {
       "version": "7.0.0",
diff --git a/src/lang/builtins.fnk b/src/lang/builtins.fnk
index 4ebfad4..12c6254 100644
--- a/src/lang/builtins.fnk
+++ b/src/lang/builtins.fnk
@@ -97,4 +97,5 @@ init_builtins = fn ctx:
     builtins: rec:
       names: []
       used: []
-      provided: []
+      overrides: {}
+      defaults: {}
diff --git a/src/lang/iterable/map.test.fnk b/src/lang/iterable/map.test.fnk
index 402d745..42b184f 100644
--- a/src/lang/iterable/map.test.fnk
+++ b/src/lang/iterable/map.test.fnk
@@ -36,7 +36,8 @@ describe 'gen 2', fn:
   it 'uses multiple custom iterable impl.', fn:
     expect
       fink2js '
-        {_map_, _filter_} = import "@fink/js-interop/iter.js"
+        {_map_} = import "./iter.fnk"
+        {_filter_} = import "./iter-filter.fnk"
         pipe [1, 2, 3]:
           map item: item * 2
           map item: item / 2
diff --git a/src/lang/iterable/map.test.fnk.snap b/src/lang/iterable/map.test.fnk.snap
index 969a0d7..1ec336e 100644
--- a/src/lang/iterable/map.test.fnk.snap
+++ b/src/lang/iterable/map.test.fnk.snap
@@ -64,7 +64,8 @@ exports[`gen 2 uses legacy iterables 1`] = `
 `;
 
 exports[`gen 2 uses multiple custom iterable impl. 1`] = `
-"import { _map_, _filter_ } from \\"@fink/js-interop/iter.js\\";
+"import { _map_ } from \\"./iter.js\\";
+import { _filter_ } from \\"./iter-filter.js\\";
 {
   let ˆpipe_result_1 = [1, 2, 3];
   ˆpipe_result_1 = _map_((item) => item * 2, false, false)(ˆpipe_result_1);
diff --git a/src/lang/module/init.fnk b/src/lang/module/init.fnk
index 8088d81..47fbe70 100644
--- a/src/lang/module/init.fnk
+++ b/src/lang/module/init.fnk
@@ -37,11 +37,9 @@ ignorable_import = fn [expr, ctx]:
       false
 
 
-# TODO: std-lib
 with_ctx = fn ctx:
   map item: [item, ctx]
 
-# TODO: std-lib
 map_acc = fn map_fn:
   foo = {}
   # TODO: should be map [item, initial_acc], acc=initial_acc:
@@ -49,6 +47,7 @@ map_acc = fn map_fn:
     ctx = match acc:
       foo: initial_acc
       else: acc
+
     [result, next_ctx] = map_fn item, ctx
     [[result, next_ctx], next_ctx]
 
@@ -67,7 +66,6 @@ add_builtin_overrides = fn expr, ctx:
         filter {right}: is_builtin right.value, ctx
         fold {right: {value: name}}, override_ctx=ctx:
           override_builtin name, uri, override_ctx
-
       [expr, next_ctx]
     else:
       [expr, ctx]
@@ -169,11 +167,19 @@ transform_module = fn node, ctx:
   [interpreter, first] = get_hashbang maybe_shebang_or_pragmas
 
   [body, end_ctx] = pipe [first, ...rest]:
-    with_ctx ctx
-    map_acc add_builtin_overrides
-    drop_if ignorable_import
-    map_acc transform_body_expr
-    collect_with_ctx ctx
+    map expr, expr_ctx=ctx:
+      [body_expr, body_ctx] = add_builtin_overrides expr, expr_ctx
+      [js_expr, next_ctx] = match body_expr:
+        ignorable_import [?, body_ctx]:
+          [false, body_ctx]
+        else:
+          transform_body_expr body_expr, body_ctx
+      [[js_expr, next_ctx], next_ctx]
+
+    drop_if fn [js]: js == false
+
+    fold [js, ctx], [jss]=[[]]:
+      [[...jss, js], ctx]
     insert_imports
 
   js = file