Function.prototype.partial

[Andrea Giammarchi]

I think his point was that in the functional programming way he is thinking
about, you don't care about `this` at all so you can shim `partial` like:

```js
Object.defineProperty(
  Function.prototype,
  'partial',
  {
    writable: true,
    configurable: true,
    value: function partial() {
      for (var a = [null], i = 0; i < arguments.length; a[++i] =
arguments[i - 1]);
      return this.bind.apply(this, a);
    }
  }
);
```

The dynamic `this` alternative seems quite straight forward anyway

```js
Object.defineProperty(
  Function.prototype,
  'partial',
  {
    writable: true,
    configurable: true,
    value: function partial() {
      for (var f = this, a = [], i = 0; i < arguments.length; a[i] =
arguments[i++]);
      return function () { a.push.apply(a, arguments); return f.apply(this,
a); };
    }
  }
);
```

Regards




On Sun, Oct 4, 2015 at 8:04 PM, Jordan Harband <ljharb at gmail.com> wrote:

> (note, it couldn't be a direct proxy to `bind` because `bind(null)`
> permanently sets the "this" value (ie, `(function () { return this
> }).bind(null).call([])` will return null or the global object, not the
> empty array. the polyfill would be a bit trickier, and couldn't use "bind"
> under the hood without changes to bind itself)
>
> On Sun, Oct 4, 2015 at 8:06 AM, Tim Ruffles <oi at truffles.me.uk> wrote:
>
>> It'd be nice to add Function.prototype.partial, which is exactly like
>> `.bind` without the `this`-setting first argument.
>>
>> Adding it would have benefits:
>>
>> - `.bind(null, ...` is newbie confusing and ugly in functional code[1]
>> - `.bind(null, ...` is a very common idiom[2]
>> - `.partial` is intention revealing: it's clear you're writing functional
>> code that doesn't care about `this`
>>
>> Adding it seems low cost, and is backwards compatible:
>>
>> - implementors could literally make it a proxy to `.bind` if they want to
>> get it done fast
>> - shimmable
>> - not new functionality, just a subset of existing functionality
>>
>> Cheers,
>>
>> Tim
>>
>> @timruffles
>>
>> - [1] I've been teaching newbies Javascript/Node.js for years, and if you
>> take a 'functions first' approach it's complexity you have to tell them to
>> ignore
>> - [2] see github -
>> https://github.com/search?l=javascript&q=%22.bind%28null%22&ref=searchresults&type=Code&utf8=%E2%9C%93
>>
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>>
>
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