feat(compose): right to left support

@vates/compose/USAGE.md

@@ -16,3 +16,15 @@ Functions may also be passed in an array:
 ```js
 const f = compose([add2, mul3])
 ```
+
+Options can be passed as first parameters:
+
+```js
+const f = compose(
+  {
+    // compose from right to left
+    right: true,
+  },
+  [add2, mul3]
+)
+```

@vates/compose/index.js

@@ -1,9 +1,21 @@
 'use strict'
 
-exports.compose = function compose(fns) {
-  if (!Array.isArray(fns)) {
+const defaultOpts = { right: false }
+
+exports.compose = function compose(opts, fns) {
+  if (Array.isArray(opts)) {
+    fns = opts
+    opts = defaultOpts
+  } else if (typeof opts === 'object') {
+    opts = Object.assign({}, defaultOpts, opts)
+    if (!Array.isArray(fns)) {
+      fns = Array.prototype.slice.call(arguments, 1)
+    }
+  } else {
     fns = Array.from(arguments)
+    opts = defaultOpts
   }
+
   const n = fns.length
   if (n === 0) {
     throw new TypeError('at least one function must be passed')
@@ -11,6 +23,11 @@ exports.compose = function compose(fns) {
   if (n === 1) {
     return fns[0]
   }
+
+  if (opts.right) {
+    fns.reverse()
+  }
+
   return function (value) {
     for (let i = 0; i < n; ++i) {
       value = fns[i](value)

@vates/compose/index.spec.js

@@ -18,4 +18,12 @@ describe('compose()', () => {
   it('accepts functions in an array', () => {
     expect(compose([add2, mul3])(5)).toBe(21)
   })
+
+  it('can apply from right to left', () => {
+    expect(compose({ right: true }, add2, mul3)(5)).toBe(17)
+  })
+
+  it('accepts options with functions in an array', () => {
+    expect(compose({ right: true }, [add2, mul3])(5)).toBe(17)
+  })
 })