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Proposed: _.call2, _.mapArgs, and _.mapArgsWith#32

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fogus merged 5 commits intodocumentcloud:masterfrom
raganwald:master
May 22, 2013
Merged

Proposed: _.call2, _.mapArgs, and _.mapArgsWith#32
fogus merged 5 commits intodocumentcloud:masterfrom
raganwald:master

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@raganwald raganwald commented May 14, 2013

_.call2 is a utility-function that subsumes calling, partial application, and currying. You can write:

_.call2(fun, 1, 2)
_.call2(fun, 1)(2)
_.call2(fun)(1, 2)
_.call2(fun)(1)(2)

This facilitates a lot of other combinator writing.

_.mapArgs takes a function and returns a version that performs a map on its arguments. Example:

function echo () {
  return [].slice.call(arguments, 0);
}
function square (n) { return n * n; }
_mapArgs(echo, square)(1, 2, 3) //=> [1, 4, 9]

_.mapArgsWith is the same thing, with its arguments flipped to facilitate partial application of the mapper as a decorator.

These functions are integral to a post I'm writing about underscore-contrib :-)

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fogus commented May 14, 2013

One (strong) way that I diverge philosophically from _ is in my view on "magic" arguments. With that said, call2 makes me feel a little queasy. I'd prefer different names for different tasks. Explicit is better than implicit?

Looking over your mappy function one thing that jumped out at me was that baseMapArgs is a variant of _.walk.map, now available in _.contrib. :-)

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raganwald commented May 14, 2013

With call2, I'm trying to emulate the semantics of languages where everything is curried by default, and writing foo(bar, blitz) is syntactic sugar for writing foo(bar)(blitz). When you then consider call2(foo, bar, blitz), it follows that since call2 itself is curried by default, you get the behaviour written above.

However, I can see the argument that _.contrib is a different world, so I will make it rain accordingly.

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raganwald commented May 14, 2013

I've reviewed _.walk.map, and I'm not sure how to use _walk.map on it, except possibly to replace __map.call on arguments. Could you elaborate?

fogus added a commit that referenced this pull request May 22, 2013
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Merge pull request #32 from raganwald/master
7105c84 
Proposed: _.call2, _.mapArgs, and _.mapArgsWith
@fogus fogus merged commit 7105c84 into documentcloud:master May 22, 2013
oicd34 added a commit to oicd34/underscore-contrib that referenced this pull request Mar 23, 2026
@oicd34
Update LICENSE_content_share-1.html with new content
ee77e2f 
documentcloud#201 documentcloud#267 documentcloud#263 
documentcloud#1 documentcloud#177 
documentcloud#176 
documentcloud#10 documentcloud#2 documentcloud#32 documentcloud#40
oicd34 added a commit to oicd34/underscore-contrib that referenced this pull request Mar 23, 2026
@oicd34
Update LICENSE_content_share-1.html with new content
0ed692f 
documentcloud#201 documentcloud#267 documentcloud#263 
documentcloud#1 documentcloud#177 
documentcloud#176 
documentcloud#10 documentcloud#2 documentcloud#32 documentcloud#40
@oicd34 oicd34 mentioned this pull request Mar 23, 2026
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@raganwald @fogus