Type Array.prototype.map/filter
We can now type `Array.prototype.{map,filter}`: * The callee is ConditionallyMutable because, although the array itself is not modified, its items flow into the lambda and may be modified there. * The argument is ConditionallyMutable because it accepts both mutable and immutable lambdas. Mutate would disallow immutable lambdas (wrong), while Read would be incorrect for mutable lambdas since calling them triggers mutation.
Joe Savona committed
May 25, 2023 at 14:50 UTC
8be5423e3bf61f88545cf90ce170aed5647b2c3c
5 files changed
+149
compiler/forget/src/HIR/ObjectShape.ts
+26
@@ -204,6 +204,32 @@ addObject(BUILTIN_SHAPES, BuiltInArrayId, [
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returnValueKind: ValueKind.Immutable,
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}),
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],
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+ [
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+ "map",
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+ addFunction(BUILTIN_SHAPES, [], {
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+ positionalParams: [],
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+ restParam: Effect.ConditionallyMutate,
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+ returnType: { kind: "Object", shapeId: BuiltInArrayId },
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+ // callee is ConditionallyMutate because items of the array
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+ // flow into the lambda and may be mutated there, even though
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+ // the array object itself is not modified
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+ calleeEffect: Effect.ConditionallyMutate,
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+ returnValueKind: ValueKind.Mutable,
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+ }),
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+ ],
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+ [
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+ "filter",
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+ addFunction(BUILTIN_SHAPES, [], {
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+ positionalParams: [],
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+ restParam: Effect.ConditionallyMutate,
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+ returnType: { kind: "Object", shapeId: BuiltInArrayId },
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+ // callee is ConditionallyMutate because items of the array
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+ // flow into the lambda and may be mutated there, even though
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+ // the array object itself is not modified
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+ calleeEffect: Effect.ConditionallyMutate,
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+ returnValueKind: ValueKind.Mutable,
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+ }),
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+ ],
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// TODO: rest of Array properties
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]);
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compiler/forget/src/__tests__/fixtures/compiler/array-map-frozen-array.expect.md
new
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@@ -0,0 +1,54 @@
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+
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+## Input
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+
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+```javascript
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+function Component(props) {
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+ const x = [];
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+ <dif>{x}</dif>;
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+ const y = x.map((item) => item);
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+ return [x, y];
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+}
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+
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+```
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+
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+## Code
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+
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+```javascript
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+import { unstable_useMemoCache as useMemoCache } from "react";
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+function Component(props) {
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+ const $ = useMemoCache(4);
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+ let t0;
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+ if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
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+ t0 = [];
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+ $[0] = t0;
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+ } else {
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+ t0 = $[0];
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+ }
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+ const x = t0;
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+ let t2;
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+ if ($[1] === Symbol.for("react.memo_cache_sentinel")) {
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+ let t1;
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+ if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
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+ t1 = (item) => item;
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+ $[2] = t1;
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+ } else {
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+ t1 = $[2];
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+ }
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+ t2 = x.map(t1);
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+ $[1] = t2;
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+ } else {
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+ t2 = $[1];
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+ }
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+ const y = t2;
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+ let t3;
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+ if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
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+ t3 = [x, y];
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+ $[3] = t3;
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+ } else {
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+ t3 = $[3];
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+ }
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+ return t3;
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+}
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+
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+```
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+
\ No newline at end of file
compiler/forget/src/__tests__/fixtures/compiler/array-map-frozen-array.js
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@@ -0,0 +1,6 @@
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+function Component(props) {
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+ const x = [];
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+ <dif>{x}</dif>;
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+ const y = x.map((item) => item);
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+ return [x, y];
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+}
compiler/forget/src/__tests__/fixtures/compiler/array-map-mutable-array-mutating-lambda.expect.md
new
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@@ -0,0 +1,55 @@
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+
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+## Input
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+
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+```javascript
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+function Component(props) {
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+ const x = [];
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+ const y = x.map((item) => {
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+ item.updated = true;
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+ return item;
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+ });
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+ return [x, y];
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+}
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+
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+```
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+
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+## Code
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+
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+```javascript
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+import { unstable_useMemoCache as useMemoCache } from "react";
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+function Component(props) {
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+ const $ = useMemoCache(4);
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+ let t1;
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+ let x;
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+ if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
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+ x = [];
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+ let t0;
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+ if ($[2] === Symbol.for("react.memo_cache_sentinel")) {
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+ t0 = (item) => {
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+ item.updated = true;
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+ return item;
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+ };
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+ $[2] = t0;
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+ } else {
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+ t0 = $[2];
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+ }
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+ t1 = x.map(t0);
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+ $[0] = t1;
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+ $[1] = x;
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+ } else {
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+ t1 = $[0];
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+ x = $[1];
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+ }
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+ const y = t1;
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+ let t2;
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+ if ($[3] === Symbol.for("react.memo_cache_sentinel")) {
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+ t2 = [x, y];
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+ $[3] = t2;
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+ } else {
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+ t2 = $[3];
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+ }
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+ return t2;
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+}
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+
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+```
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+
\ No newline at end of file
compiler/forget/src/__tests__/fixtures/compiler/array-map-mutable-array-mutating-lambda.js
new
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@@ -0,0 +1,8 @@
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+function Component(props) {
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+ const x = [];
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+ const y = x.map((item) => {
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+ item.updated = true;
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+ return item;
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+ });
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+ return [x, y];
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+}