initial version of inlining _List_fromArray

src/experiments/inlineListFromArray.ts

@@ -0,0 +1,68 @@
+import ts from 'typescript';
+
+// `
+//   var _List_Nil = { $: "[]" };
+
+//   function _List_Cons(hd, tl) {
+//     return { $: "::", a: hd, b: tl };
+//   }
+
+//   var _List_cons = F2(_List_Cons);
+
+//   function _List_fromArray(arr) {
+//     var out = _List_Nil;
+//     for (var i = arr.length; i--; ) {
+//       out = _List_Cons(arr[i], out);
+//     }
+//     return out;
+//   }
+// `;
+// `
+//       _List_fromArray([
+//        "a",
+//         "b",
+//         "c",
+//       ])
+// `;
+
+const LIST_FROM_ARRAY_F_NAME = '_List_fromArray';
+const LIST_NIL_NAME = '_List_Nil';
+const LIST_CONS_F_NAME = '_List_cons';
+
+const listNil = ts.createIdentifier(LIST_NIL_NAME);
+const listConsCall = ts.createIdentifier(LIST_CONS_F_NAME);
+
+const appendToFront = (
+  expression: ts.Expression,
+  list: ts.Expression
+): ts.Expression => {
+  return ts.createCall(listConsCall, undefined, [expression, list]);
+};
+
+export const createInlineListFromArrayTransformer = (): ts.TransformerFactory<ts.SourceFile> => context => {
+  return sourceFile => {
+    const visitor = (node: ts.Node): ts.VisitResult<ts.Node> => {
+      // detects [exp](..)
+      if (ts.isCallExpression(node)) {
+        const expression = node.expression;
+        // detects _List_fromArray(..)
+        if (
+          ts.isIdentifier(expression) &&
+          expression.text === LIST_FROM_ARRAY_F_NAME &&
+          node.arguments.length === 1
+        ) {
+          const [arrayLiteral] = node.arguments;
+
+          // detects _List_fromArray([..])
+          if (ts.isArrayLiteralExpression(arrayLiteral)) {
+            return arrayLiteral.elements.reduceRight(appendToFront, listNil);
+          }
+        }
+      }
+
+      return ts.visitEachChild(node, visitor, context);
+    };
+
+    return ts.visitNode(sourceFile, visitor);
+  };
+};

src/index.ts

@@ -9,6 +9,8 @@ import {
   createFuncInlineTransformer,
 } from './experiments/inlineWrappedFunctions';
 
+import { createInlineListFromArrayTransformer } from './experiments/inlineListFromArray';
+
 const elmOutput = `
 var $elm$core$Maybe$Nothing = {$: 'Nothing'};
 
@@ -22,6 +24,8 @@ var $author$project$Main$Three = F3(
   });
 
 var _v1 = A3($author$project$Main$Three, a, b, c);
+
+_List_fromArray(['a', 'b', 'c']);
 `;
 
 const source = ts.createSourceFile('elm.js', elmOutput, ts.ScriptTarget.ES2018);
@@ -68,10 +72,21 @@ const [sourceWithSplittedFunctions] = ts.transform(newFile, [
 console.log(printer.printFile(sourceWithSplittedFunctions));
 console.log(collectedSplits);
 
-console.log('----------AFTER SPLIT TRANSFORM ----------------');
+console.log('----------AFTER INLINE A(n) TRANSFORM ----------------');
 const funcInlineTransformer = createFuncInlineTransformer(collectedSplits);
 const [sourceWithInlinedFuntioncs] = ts.transform(sourceWithSplittedFunctions, [
   funcInlineTransformer,
 ]).transformed;
 
 console.log(printer.printFile(sourceWithInlinedFuntioncs));
+
+console.log(
+  '----------AFTER INLINE _List_fromArray TRANSFORM ----------------'
+);
+const inlineListFromArrayCalls = createInlineListFromArrayTransformer();
+const [sourceWithInlinedListFromArr] = ts.transform(
+  sourceWithInlinedFuntioncs,
+  [inlineListFromArrayCalls]
+).transformed;
+
+console.log(printer.printFile(sourceWithInlinedListFromArr));