Support ES modules (#145)

Author: kl0tl

src/to-javascript.js

@@ -62,16 +62,16 @@ function makeBundleJS(psModule) {
   return Promise.resolve(result);
 }
 
-// Replace require paths to output files generated by psc with paths
+// Replace require and import paths to output files generated by psc with paths
 // to purescript sources, which are then also run through this loader.
 // Additionally, the imports replaced are tracked so that in the event
 // the compiler fails to compile the PureScript source, we can tack on
 // any new imports in order to allow webpack to watch the new files
 // before they have been successfully compiled.
 function makeJS(psModule, psModuleMap, js) {
-  const requireRE = /require\(['"]\.\.\/([\w\.]+)(?:\/index\.js)?['"]\)/g;
-
-  const foreignRE = /require\(['"]\.\/foreign(?:\.js)?['"]\)/g;
+  const dependencyRE = /(?:require\(|from\s*)['"]\.\.\/([\w\.]+)(?:\/index\.js)?['"]/g;
+  const requireRE = /^require/;
+  const foreignRE = /(?:require\(|from\s*)['"]\.\/foreign(?:\.js)?['"]/g;
 
   const name = psModule.name;
 
@@ -80,11 +80,11 @@ function makeJS(psModule, psModuleMap, js) {
   var replacedImports = [];
 
   const result = js
-    .replace(requireRE, (m, p1) => {
+    .replace(dependencyRE, (m, p1) => {
       const moduleValue = psModuleMap[p1];
 
       if (!moduleValue) {
-        debug('module %s was not found in the map, replacing require with null', p1);
+        debug('module %s was not found in the map, replacing dependency with null', p1);
 
         return 'null';
       }
@@ -93,13 +93,17 @@ function makeJS(psModule, psModuleMap, js) {
 
         replacedImports.push(p1);
 
-        return `require("${escapedPath}")`;
+        return requireRE.test(m)
+          ? `require("${escapedPath}"`
+          : `from "${escapedPath}"`;
       }
     })
-    .replace(foreignRE, () => {
+    .replace(foreignRE, (m) => {
       const escapedPath = jsStringEscape(psModuleMap[name].ffi);
 
-      return `require("${escapedPath}")`;
+      return requireRE.test(m)
+        ? `require("${escapedPath}"`
+        : `from "${escapedPath}"`;
     })
   ;