Hi,
I just wanted to bring up IMO important limitation of arrow functions. They do
solve unbound `this` issues when used as a callback, but they also introduce
unfortunate limitation. Arrow functions can not really be
used as methods. For example it was great that in JS one could write a function
that could be used as
a method or as function:
function map(f) {
return this.reduce((result, value) => result.concat([ f(value) ]), [])
}
// Use as method
foo.map = map;
foo.map((x) => x + 1)
// Use as function
map.call(bar, (x) => x + 1)
I would say still is unfortunate that such reusable functions had do be called
via special `.call` but never the less code sharing was simple to do.
Now arrow functions as they stand today can not be used in that manner as
`this` refers to the outer scope `this` for a good reason. But it still would
be nice to allow reusing them as methods, in fact they could be even solve
current `map.call(…)`. What I'd like to propose is borrow successful idea from
other languages and make:
foo.map((x) => x + 1)
be a sugar for
map(foo, (x) => x + 1)
If `map` is an arrow function
That would make (arrow) functions a lot more composable:
var map = (list, f) =>
list.reduce((result, value) => result.concat([ f(value) ]), [])
List.prototype.map = map
List().map((x) => x + 1)
or
map(List(), (x) => x + 1)
or
map([ 1, 2, 3 ], (x) => x + 1)
I think this would make a good synergy of OO and functional styles in JS
Regards
--
Irakli Gozalishvili
Web: http://www.jeditoolkit.com/
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