[FEATURE] add call snippet (#309)

snippets/call.md

@@ -0,0 +1,14 @@
+### call
+
+Given a key and a set of arguments, call them when given a context. Primarily useful in composition.
+
+Use a closure to call a stored key with stored arguments.
+
+```js
+const call = ( key, ...args ) => context => context[ key ]( ...args );
+/*
+Promise.resolve( [ 1, 2, 3 ] ).then( call('map', x => 2 * x ) ).then( console.log ) //[ 2, 4, 6 ]
+const map = call.bind(null, 'map')
+Promise.resolve( [ 1, 2, 3 ] ).then( map( x => 2 * x ) ).then( console.log ) //[ 2, 4, 6 ]
+*/
+```