wu.js -- A lazy, functional Javascript library

http://fitzgen.github.com/wu.js/

by mnemonik • 16 years ago

79 24 16 years ago

fitzgen.github.com

mnemonik6• 16 years ago

Hey everyone, this is my baby and I would love to get some feedback.

If you have any questions, don't hesitate to ask anything (but I might disappear for a couple hours because I have a final coming up).

Thanks!

mnemonik6• 16 years ago

(Back from my final now (it went well)).

yacin• 16 years ago

Killer name.

mnemonik6• 16 years ago

Thanks :)

If anyone isn't aware, it is named after the infamous Wu-Tang Clan: http://www.youtube.com/watch?v=0OEcZqG9xnE

erlanger• 16 years ago

you can sell wu wear

kno• 16 years ago

the part I loved the most: that ain't nuthin' ta f*ck wit.

jashkenas• 16 years ago

One interesting idea (for JS) is defining functions as pattern matches on the arguments. Here's a factorial from the docs:

    >>> var factorial = wu.match(
    ...   [ 0 ],      1,
    ...   [ Number ], function (n) { return n * factorial(n - 1); }
    ... );
    >>> factorial(5);
    120

alrex0213• 16 years ago

Ok, now that is very neat.

adamdecaf• 16 years ago

That took me a bit to understand what is going on, but now that I see it it really is cool.

Each line (e.g. [ 0 ], 1,) represents something similar to (key,value) pairs. So, in the first example any input that matches the array ([0]) (or [1,293,592] for that matter) would return the "value", or in this case "1".

It gets better with the following line, if the input matches a ([Number]) then it returns "function (n) { return n * factorial(n-1); }", a common recursive algorithm for finding a factorial.

Really, a nice looking framework all around.

johnswamps• 16 years ago

Yep, it's pretty neat. If you're familiar with haskell (I'm not sure if haskell invented it, but it's probably the most well-known example) this will be familiar to you. For example, factorial could be written as:

fac 0 = 1

fac n = n * fac(n-1)

xtho• 16 years ago

How many function objects are created to generate that result? From a certain point of view, that is interesting too of course.

silentbicycle2• 16 years ago

Without looking at the source: it could either generate a decision tree made of nested ifs and case statements (or the CPS equivalent), or it could just do a naive linear search over each list element. That's probably good enough until you have long lists of alternatives or structural matching against whole trees.

I have a quick hack of a Lua library that does pattern matching with linear search. Whenever I get around to making it actually do analysis and compile search functions, I'll put it on github. (The patterns can have variable captures in them, too.)

bramstein• 16 years ago

I played with the same idea a couple of years ago and published a library for it: * http://www.bramstein.com/projects/jfun/ * http://www.bramstein.com/articles/pattern-matching.html * http://www.bramstein.com/articles/advanced-pattern-matching....

Although the implementation works great, I couldn't get past the (obvious) syntax issues and never actually used it in production code. It was an interesting experiment though, especially when combined with Sjoerd Visscher's algebraic data type library (http://w3future.com/weblog/stories/2008/06/16/adtinjs.xml).

alrex0213• 16 years ago

I'd be very interested to see some real-world cases for lazy sequences in context of client-side JavaScript interpretation.

The "Why?" section doesn't seem to have any information in the docs.

mnemonik6• 16 years ago

Aware of the "Why" section issue, however don't have time for a fix right now, I'm about to head off to a final exam.

I will be trying to get a "real world" and practical example that is a little more in depth out soon, but my first goal was total API documentation coverage.

Thanks for the interest,

Nick

mnemonik6• 16 years ago

That dead link has been removed now.

sciolistse• 16 years ago

I've had a bit of the same issue.. I wrote a similar library a while back, and was hard pressed to find a situation in which JavaScript's method invocation overhead didn't overshadow much of the benefit of the lazy execution.

They're fun to write though, it'd be interesting to see if there are any useful applications.

apgwoz• 16 years ago

> I'd be very interested to see some real-world cases for lazy sequences in context of client-side JavaScript interpretation.

Please remember that JS is no longer just client-side stuff. Node.js, and other implementations have become quite popular in some circles for doing server side things.

alrex0213• 16 years ago

> Please remember ...

JavaScript runs on the server side? ;-)

Quote from wu.js site:

"Works great in the browser".

Hence my genuine interest in understanding the not so obvious real-world cases for lazy-seq and client-side programming.

sharkbrainguy2• 16 years ago

Just quietly, I've written a library that provides lazy sequences as MooTools Classes if anyone is that way inclined.

http://github.com/sharkbrainguy/sequences.js

Some basic examples:

http://jsfiddle.net/Zh7pR/

It does suffer from the whole "what's the point" problem.

olliesaunders• 16 years ago

I like the idea of these functional JS libraries but I'm always concerned about the performance hit.

sharkbrainguy2• 16 years ago

underscore.js provides alot of functional (not lazy) tools with solid performance.

http://documentcloud.github.com/underscore/

Check out the benchmarks:

http://documentcloud.github.com/underscore/test/test.html

wu.js -- A lazy, functional Javascript library

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