Merge pull request #1 from unsplash/fix/various

Various small fixes
unsplash · Jul 5, 2019 · 81228d8 · 81228d8
2 parents 5289c82 + 519fe44
commit 81228d8
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Showing 4 changed files with 47 additions and 11 deletions.
diff --git a/README.md b/README.md
@@ -55,6 +55,10 @@ const result: number = pipeWith(1, add1, times2);
 assert.strictEqual(result, 4);
 ```
 
+## Note about type safety
+
+`pipe` and `pipeWith` currently support up to 9 functions. If more than 9 functions are passed, type safety will be lost. If need be, we are open to adding more overloads to avoid this.
+
 ## Development
 
 ```

diff --git a/package.json b/package.json
@@ -24,10 +24,8 @@
   "files": [
     "target"
   ],
-  "dependencies": {
-    "@types/node": "^12.0.10"
-  },
   "devDependencies": {
+    "@types/node": "^12.0.10",
     "prettier": "^1.18.2",
     "source-map-support": "^0.5.12",
     "tslint": "^5.18.0",

diff --git a/src/index.ts b/src/index.ts
@@ -1,7 +1,9 @@
-type AnyFunction = (...params: unknown[]) => unknown;
+type AnyFunction = (...params: any[]) => any;
+type UnknownFunction = (...params: unknown[]) => unknown;
 
 // Copied from https://github.com/gcanti/fp-ts/blob/1.15.0/src/function.ts#L209 with some
 // modifications to make the first function allow multiple parameters.
+export function pipe<A extends unknown[], B>(ab: (...a: A) => B): (...args: A) => B;
 export function pipe<A extends unknown[], B, C>(
     ab: (...a: A) => B,
     bc: (b: B) => C,
@@ -62,14 +64,16 @@ export function pipe<A extends unknown[], B, C, D, E, F, G, H, I, J>(
     hi: (h: H) => I,
     ij: (i: I) => J,
 ): (...args: A) => J;
-export function pipe(...fns: AnyFunction[]): AnyFunction {
+export function pipe(...fns: AnyFunction[]): UnknownFunction;
+export function pipe(...fns: UnknownFunction[]): UnknownFunction {
     return (...initialParams: unknown[]): unknown =>
         fns.reduce<unknown>((value, fn, index) => {
             const params = index === 0 ? (value as unknown[]) : [value];
             return fn(...params);
         }, initialParams);
 }
 
+export function pipeWith<A, B>(a: A, ab: (a: A) => B): B;
 export function pipeWith<A, B, C>(a: A, ab: (a: A) => B, bc: (b: B) => C): C;
 export function pipeWith<A, B, C, D>(a: A, ab: (a: A) => B, bc: (b: B) => C, cd: (c: C) => D): D;
 export function pipeWith<A, B, C, D, E>(
@@ -129,10 +133,7 @@ export function pipeWith<A, B, C, D, E, F, G, H, I, J>(
     hi: (h: H) => I,
     ij: (i: I) => J,
 ): J;
-export function pipeWith(value: unknown, ...fns: AnyFunction[]) {
-    return pipe(
-        // TODO:
-        // @ts-ignore
-        ...fns,
-    )(value);
+export function pipeWith(a: unknown, ...fns: AnyFunction[]): unknown;
+export function pipeWith(value: unknown, ...fns: UnknownFunction[]): unknown {
+    return pipe(...fns)(value);
 }
diff --git a/src/tests.ts b/src/tests.ts
@@ -18,6 +18,7 @@ const it = (name: string, fn: () => void) => {
 describe('pipe', () => {
     it('works when first function has single param', () => {
         // One test for each overload
+        assert.strictEqual(pipe(singleParamFnAdd1)(1), 2);
         assert.strictEqual(
             pipe(
                 singleParamFnAdd1,
@@ -102,6 +103,21 @@ describe('pipe', () => {
             )(1),
             47,
         );
+        assert.strictEqual(
+            pipe(
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+            )(1),
+            94,
+        );
     });
 
     it('works when first function has multiple params', () => {
@@ -118,6 +134,7 @@ describe('pipe', () => {
 describe(pipeWith.name, () => {
     it('works', () => {
         // One test for each overload
+        assert.strictEqual(pipeWith(1, singleParamFnAdd1), 2);
         assert.strictEqual(pipeWith(1, singleParamFnAdd1, singleParamFnTimes2), 4);
         assert.strictEqual(
             pipeWith(1, singleParamFnAdd1, singleParamFnTimes2, singleParamFnAdd1),
@@ -198,5 +215,21 @@ describe(pipeWith.name, () => {
             ),
             47,
         );
+        assert.strictEqual(
+            pipeWith(
+                1,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+                singleParamFnAdd1,
+                singleParamFnTimes2,
+            ),
+            94,
+        );
     });
 });