4 ms·

Curried Javascript Functions

30 points by ccarpenterg 17y ago

troels 17y ago
Oldie but goodie. If you liked that, you might like this too: [Higher Order Programming in Javascript](http://w3future.com/html/stories/hop.xml http://w3future.com/html/stories/hop.xml)
apu 17y ago
If you already know all about higher-order programming and just want a javascript library with all the haskell/ML-style goodness, I highly recommend O. Steele's Functional library: http://osteele.com/sources/javascript/functional/ http://osteele.com/sources/javascript/functional/ If nothing else, then his lambda() implementation with strings should be enough to convince you to use it.
ilyak 17y ago
Prototype has curry() and bind() methods on functions for some time. http://prototypejs.org/api/function http://prototypejs.org/api/function String.prototype.splitOnSpaces = String.prototype.split.curry(" "); "foo bar baz thud".splitOnSpaces(); //-> ["foo", "bar", "baz", "thud"]
- lhorie 17y ago
  This: "foo bar baz thud".splitOnSpaces(); //-> ["foo", "bar", "baz", "thud"] can be written like this: $w("foo bar baz thud")
jganetsk 17y ago
Here's an implementation that I think is shorter, simpler to understand, easier to use, and doesn't require modifying existing functions for currification function curry(fn) { var wrappedFnMaker = function(accArgs) { return function() { var effectiveArgs = accArgs.concat(Array.prototype.slice.call(arguments)); if (effectiveArgs.length >= fn.length) { return fn.apply(this, effectiveArgs); } else { return wrappedFnMaker(effectiveArgs); } }; } return wrappedFnMaker([]); } add = curry(function(a,b,c) { return a + b + c; });
- marcmarc 17y ago
  Here's my take: function curry(fn, args) { if (typeof args == "undefined" || args.length < fn.length) return function() { if (typeof args == "undefined") args = []; return curry(fn, args.concat(Array.prototype.slice.call(arguments))); }; return fn.apply(this, args); } var add = curry(function(a, b, c) { return a + b + c;});
  - jganetsk 17y ago
    Both of our implementations have broken this. Damn you, Javascript this. In principle, these two lines of code should always produce the same result: foo.bar(1,2) and foo.bar(1)(2) And they won't necessarily in our case, if the function uses this.
  - deleted 17y ago
    [deleted]
  - shaunxcode 17y ago
    Here is curry in php 5.3 function curry(){ $args = func_get_args(); $fn = array_shift($args); return function() use(&$fn, &$args) { $nargs = func_get_args(); foreach($nargs as $narg) $args[] = $narg; return call_user_func_array($fn, $args); }; } $add20 = curry(function($a, $b){return $a + $b;}, 20); echo $add20(5); #25
bodhi 17y ago
What's the deal with the stuff in the footer of this page? "The original page disappeared a couple of years ago. This is an unauthorized copy." It links to http://www.svendtofte.com/code/curried_javascript/ http://www.svendtofte.com/code/curried_javascript/ which I guess is the original article?
axod 17y ago
Currying looks horrible IMHO. It's like goto but worse. Can anyone give a real life example of why it's useful or desired?

30 points by ccarpenterg 17y ago

Oldie but goodie. If you liked that, you might like this too: [Higher Order Programming in Javascript](http://w3future.com/html/stories/hop.xml http://w3future.com/html/stories/hop.xml)

apu 17y ago

If you already know all about higher-order programming and just want a javascript library with all the haskell/ML-style goodness, I highly recommend O. Steele's Functional library: http://osteele.com/sources/javascript/functional/ http://osteele.com/sources/javascript/functional/ If nothing else, then his lambda() implementation with strings should be enough to convince you to use it.

ilyak 17y ago

Prototype has curry() and bind() methods on functions for some time. http://prototypejs.org/api/function http://prototypejs.org/api/function String.prototype.splitOnSpaces = String.prototype.split.curry(" "); "foo bar baz thud".splitOnSpaces(); //-> ["foo", "bar", "baz", "thud"]

lhorie 17y ago
This: "foo bar baz thud".splitOnSpaces(); //-> ["foo", "bar", "baz", "thud"] can be written like this: $w("foo bar baz thud")

jganetsk 17y ago

Here's an implementation that I think is shorter, simpler to understand, easier to use, and doesn't require modifying existing functions for currification function curry(fn) { var wrappedFnMaker = function(accArgs) { return function() { var effectiveArgs = accArgs.concat(Array.prototype.slice.call(arguments)); if (effectiveArgs.length >= fn.length) { return fn.apply(this, effectiveArgs); } else { return wrappedFnMaker(effectiveArgs); } }; } return wrappedFnMaker([]); } add = curry(function(a,b,c) { return a + b + c; });

marcmarc 17y ago
Here's my take: function curry(fn, args) { if (typeof args == "undefined" || args.length < fn.length) return function() { if (typeof args == "undefined") args = []; return curry(fn, args.concat(Array.prototype.slice.call(arguments))); }; return fn.apply(this, args); } var add = curry(function(a, b, c) { return a + b + c;});
- jganetsk 17y ago
  Both of our implementations have broken this. Damn you, Javascript this. In principle, these two lines of code should always produce the same result: foo.bar(1,2) and foo.bar(1)(2) And they won't necessarily in our case, if the function uses this.
- deleted 17y ago
  [deleted]
- shaunxcode 17y ago
  Here is curry in php 5.3 function curry(){ $args = func_get_args(); $fn = array_shift($args); return function() use(&$fn, &$args) { $nargs = func_get_args(); foreach($nargs as $narg) $args[] = $narg; return call_user_func_array($fn, $args); }; } $add20 = curry(function($a, $b){return $a + $b;}, 20); echo $add20(5); #25

bodhi 17y ago

What's the deal with the stuff in the footer of this page? "The original page disappeared a couple of years ago. This is an unauthorized copy." It links to http://www.svendtofte.com/code/curried_javascript/ http://www.svendtofte.com/code/curried_javascript/ which I guess is the original article?

axod 17y ago

Currying looks horrible IMHO. It's like goto but worse. Can anyone give a real life example of why it's useful or desired?