Advanced JavaScript: Compose function

http://javascriptweblog.wordpress.com/2010/04/14/compose-functions-as-building-blocks/

by heseltine • 16 years ago

18 6 16 years ago

javascriptweblog.wordpress.com

apphacker3• 16 years ago

This is simply bind which will be in future versions of JavaScript. http://ejohn.org/blog/ecmascript-5-strict-mode-json-and-more... It has been available in dojo as dojo.hitch, goog.bind, $.hitch in a jQuery plugin.

ionfish• 16 years ago

No, it's function composition as seen in e.g. pure functional programming languages like Haskell:

(.) :: (b -> c) -> (a -> b) -> a -> c

Except that of course in an impure language like JavaScript if you compose some function f with another function g, either or both functions could have side effects (via I/O, mutation etc.) that break referential transparency.

After a quick glance at the Prototype code, the bind function isn't merely changing which object the name 'this' is bound to, it also allows a kind of currying. However, this still isn't function composition.

apphacker3• 16 years ago

Look at the source of what dojo.hitch does or google.bind. It is the exact same thing. Whoever down-voted me obviously doesn't know JavaScript. Voting on comments is such a dumb idea. Popularity does not equal right. Right is simply right.

heseltine• 16 years ago

@apphacker - are you sure? I thought bind assigned the value of 'this' in a function.

pg• 16 years ago

We have nested comments here. You don't have to use @; you can reply directly.

apphacker3• 16 years ago

What is 'call' doing in that function? Check out dojo.hitch:

http://www.google.com/codesearch/p?hl=en#1oUPVh-C1Wg/trunk/e...

Advanced JavaScript: Compose function

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