diff --git a/snippets/pipeAsyncFunctions.md b/snippets/pipeAsyncFunctions.md new file mode 100644 index 000000000..95423ce28 --- /dev/null +++ b/snippets/pipeAsyncFunctions.md @@ -0,0 +1,22 @@ +### pipeAsyncFunctions + +Performs left-to-right function composition. + +Use `Array.reduce()` with the spread operator (`...`) to perform left-to-right function composition using `Promise.then()`. The functions can return a combination of: simple values, `Promise`'s, or they can be defined as `async` ones returning through `await`. +All functions must be unary. + +```js +const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Promise.resolve(arg)); +``` + +```js +const sum = pipeAsyncFunctions( + x => x + 1, + x => new Promise(resolve => setTimeout(() => resolve(x + 2), 1000)), + x => x + 3, + async x => (await x) + 4 +); +(async () => { + console.log(await sum(5)); // 15 (after one second) +})(); +``` diff --git a/tag_database b/tag_database index 9a84845df..f5baa13d8 100644 --- a/tag_database +++ b/tag_database @@ -169,6 +169,7 @@ partition:array,object,function percentile:math pick:object,array pickBy:object,array,function +pipeAsyncFunctions:adapter,function,async pipeFunctions:adapter,function pluralize:string powerset:math diff --git a/test/pipeAsyncFunctions/pipeAsyncFunctions.js b/test/pipeAsyncFunctions/pipeAsyncFunctions.js new file mode 100644 index 000000000..09091affc --- /dev/null +++ b/test/pipeAsyncFunctions/pipeAsyncFunctions.js @@ -0,0 +1,2 @@ +const pipeAsyncFunctions = (...fns) => arg => fns.reduce((p, f) => p.then(f), Promise.resolve(arg)); +module.exports = pipeAsyncFunctions \ No newline at end of file diff --git a/test/pipeAsyncFunctions/pipeAsyncFunctions.test.js b/test/pipeAsyncFunctions/pipeAsyncFunctions.test.js new file mode 100644 index 000000000..7a4ae346e --- /dev/null +++ b/test/pipeAsyncFunctions/pipeAsyncFunctions.test.js @@ -0,0 +1,24 @@ +const test = require('tape'); +const pipeAsyncFunctions = require('./pipeAsyncFunctions.js'); + +test('Testing pipeAsyncFunctions', async (t) => { + //For more information on all the methods supported by tape + //Please go to https://github.com/substack/tape + t.true(typeof pipeAsyncFunctions === 'function', 'pipeAsyncFunctions is a Function'); + //t.deepEqual(pipeAsyncFunctions(args..), 'Expected'); + //t.equal(pipeAsyncFunctions(args..), 'Expected'); + //t.false(pipeAsyncFunctions(args..), 'Expected'); + //t.throws(pipeAsyncFunctions(args..), 'Expected'); + t.equal( + await pipeAsyncFunctions( + (x) => x + 1, + (x) => new Promise((resolve) => setTimeout(() => resolve(x + 2), 0)), + (x) => x + 3, + async (x) => await x + 4, + ) + (5), + 15, + 'pipeAsyncFunctions result should be 15' + ); + t.end(); +}); \ No newline at end of file