[hir] Move Types to a separate file

--- 

Move types around in preparation for next PR #1335. No changes in impl, types, 
or functions.

compiler/forget/src/HIR/HIR.ts

@@ -8,7 +8,7 @@
 import * as t from "@babel/types";
 import invariant from "invariant";
 import { Environment } from "./Environment";
-import { Hook } from "./Hooks";
+import { Type } from "./Types";
 
 // *******************************************************************************************
 // *******************************************************************************************
@@ -763,121 +763,6 @@ export function makeInstructionId(id: number): InstructionId {
   return id as InstructionId;
 }
 
-export type Type =
-  | PrimitiveType
-  | HookType
-  | FunctionType
-  | ObjectType
-  | PhiType
-  | PolyType
-  | TypeVar;
-export type PrimitiveType = { kind: "Primitive" };
-export type FunctionType = {
-  kind: "Function";
-};
-export type HookType = {
-  kind: "Hook";
-  definition: Hook;
-};
-export type ObjectType = { kind: "Object" };
-export type TypeVar = {
-  kind: "Type";
-  id: TypeId;
-};
-export type PolyType = {
-  kind: "Poly";
-};
-export type PhiType = {
-  kind: "Phi";
-  operands: Array<Type>;
-};
-
-/**
- * Simulated opaque type for TypeId to prevent using normal numbers as ids
- * accidentally.
- */
-const opaqueTypeId = Symbol();
-export type TypeId = number & { [opaqueTypeId]: "IdentifierId" };
-
-export function makeTypeId(id: number): TypeId {
-  invariant(
-    id >= 0 && Number.isInteger(id),
-    "Expected instruction id to be a non-negative integer"
-  );
-  return id as TypeId;
-}
-
-let typeCounter = 0;
-export function makeType(): TypeVar {
-  return {
-    kind: "Type",
-    id: makeTypeId(typeCounter++),
-  };
-}
-
-export function typeEquals(tA: Type, tB: Type): boolean {
-  if (tA.kind !== tB.kind) return false;
-  return (
-    typeVarEquals(tA, tB) ||
-    funcTypeEquals(tA, tB) ||
-    hookTypeEquals(tA, tB) ||
-    objectTypeEquals(tA, tB) ||
-    primitiveTypeEquals(tA, tB) ||
-    polyTypeEquals(tA, tB) ||
-    phiTypeEquals(tA, tB)
-  );
-}
-
-function typeVarEquals(tA: Type, tB: Type): boolean {
-  if (tA.kind === "Type" && tB.kind === "Type") {
-    return tA.id === tB.id;
-  }
-  return false;
-}
-
-function typeKindCheck(tA: Type, tb: Type, type: string): boolean {
-  return tA.kind === type && tb.kind === type;
-}
-
-function primitiveTypeEquals(tA: Type, tB: Type): boolean {
-  return typeKindCheck(tA, tB, "Primitive");
-}
-
-function polyTypeEquals(tA: Type, tB: Type): boolean {
-  return typeKindCheck(tA, tB, "Poly");
-}
-
-function objectTypeEquals(tA: Type, tB: Type): boolean {
-  return typeKindCheck(tA, tB, "Object");
-}
-
-function funcTypeEquals(tA: Type, tB: Type): boolean {
-  return typeKindCheck(tA, tB, "Function");
-}
-
-function hookTypeEquals(tA: Type, tB: Type): boolean {
-  return (
-    tA.kind === "Hook" && tB.kind === "Hook" && tA.definition === tB.definition
-  );
-}
-
-function phiTypeEquals(tA: Type, tB: Type): boolean {
-  if (tA.kind === "Phi" && tB.kind === "Phi") {
-    if (tA.operands.length !== tB.operands.length) {
-      return false;
-    }
-
-    let operands = new Set(tA.operands);
-    for (let i = 0; i < tB.operands.length; i++) {
-      if (!operands.has(tB.operands[i])) {
-        return false;
-      }
-    }
-  }
-
-  return false;
-}
-
 export function isObjectType(id: Identifier): boolean {
   return id.type.kind === "Object";
 }
@@ -889,3 +774,5 @@ export function isPrimitiveType(id: Identifier): boolean {
 export function isHookType(id: Identifier): boolean {
   return id.type.kind === "Hook";
 }
+
+export * from "./Types";

compiler/forget/src/HIR/Types.ts

@@ -0,0 +1,123 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import invariant from "invariant";
+import { Hook } from "./Hooks";
+
+export type Type =
+  | PrimitiveType
+  | HookType
+  | FunctionType
+  | ObjectType
+  | PhiType
+  | PolyType
+  | TypeVar;
+export type PrimitiveType = { kind: "Primitive" };
+export type FunctionType = {
+  kind: "Function";
+};
+export type HookType = {
+  kind: "Hook";
+  definition: Hook;
+};
+export type ObjectType = { kind: "Object" };
+export type TypeVar = {
+  kind: "Type";
+  id: TypeId;
+};
+export type PolyType = {
+  kind: "Poly";
+};
+export type PhiType = {
+  kind: "Phi";
+  operands: Array<Type>;
+};
+
+/**
+ * Simulated opaque type for TypeId to prevent using normal numbers as ids
+ * accidentally.
+ */
+const opaqueTypeId = Symbol();
+export type TypeId = number & { [opaqueTypeId]: "IdentifierId" };
+
+export function makeTypeId(id: number): TypeId {
+  invariant(
+    id >= 0 && Number.isInteger(id),
+    "Expected instruction id to be a non-negative integer"
+  );
+  return id as TypeId;
+}
+
+let typeCounter = 0;
+export function makeType(): TypeVar {
+  return {
+    kind: "Type",
+    id: makeTypeId(typeCounter++),
+  };
+}
+
+export function typeEquals(tA: Type, tB: Type): boolean {
+  if (tA.kind !== tB.kind) return false;
+  return (
+    typeVarEquals(tA, tB) ||
+    funcTypeEquals(tA, tB) ||
+    hookTypeEquals(tA, tB) ||
+    objectTypeEquals(tA, tB) ||
+    primitiveTypeEquals(tA, tB) ||
+    polyTypeEquals(tA, tB) ||
+    phiTypeEquals(tA, tB)
+  );
+}
+
+function typeVarEquals(tA: Type, tB: Type): boolean {
+  if (tA.kind === "Type" && tB.kind === "Type") {
+    return tA.id === tB.id;
+  }
+  return false;
+}
+
+function typeKindCheck(tA: Type, tb: Type, type: string): boolean {
+  return tA.kind === type && tb.kind === type;
+}
+
+function primitiveTypeEquals(tA: Type, tB: Type): boolean {
+  return typeKindCheck(tA, tB, "Primitive");
+}
+
+function polyTypeEquals(tA: Type, tB: Type): boolean {
+  return typeKindCheck(tA, tB, "Poly");
+}
+
+function objectTypeEquals(tA: Type, tB: Type): boolean {
+  return typeKindCheck(tA, tB, "Object");
+}
+
+function funcTypeEquals(tA: Type, tB: Type): boolean {
+  return typeKindCheck(tA, tB, "Function");
+}
+
+function hookTypeEquals(tA: Type, tB: Type): boolean {
+  return (
+    tA.kind === "Hook" && tB.kind === "Hook" && tA.definition === tB.definition
+  );
+}
+
+function phiTypeEquals(tA: Type, tB: Type): boolean {
+  if (tA.kind === "Phi" && tB.kind === "Phi") {
+    if (tA.operands.length !== tB.operands.length) {
+      return false;
+    }
+
+    let operands = new Set(tA.operands);
+    for (let i = 0; i < tB.operands.length; i++) {
+      if (!operands.has(tB.operands[i])) {
+        return false;
+      }
+    }
+  }
+
+  return false;
+}