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[ANN] Ruby Murray - Sub::Curry on Ruby Acid

Ross Bamford

2/21/2006 3:09:00 PM

Ruby Murray, a Ruby port of Perl's Sub::Curry (with added Ruby
goodness), is now available in it's first 0.1.2 release.

Ruby Murray allows block arguments to be supplied prior to calling (to
be 'curried') and also supports a range of features that allow arguments
to be populated in arbitrary order and with complex processing.

Out now: http://rubymurray.ruby... or 'gem install rubymurray'

(yes, it's my solution to quiz 64, I thought it might be nice to release
it but only just got round to it).

--
Ross Bamford - rosco@roscopeco.REMOVE.co.uk
5 Answers

Meinrad Recheis

2/21/2006 5:08:00 PM

0

cool naming, nice functionality, easy using.
AFAIK this is a instantiation of the Design Pattern called "Command" by
the Gang of Four.
i can not imagine a problem where i needed such flexible argument list.
can anyone provide a motivation example in ruby?
i'd suggest to add a small sample of usage to the docs.
-- henon

James Herdman

2/21/2006 5:26:00 PM

0

On 2006-02-21 12:08:22 -0500, "henon" <meinrad.recheis@gmail.com> said:

> cool naming, nice functionality, easy using.
> AFAIK this is a instantiation of the Design Pattern called "Command" by
> the Gang of Four.
> i can not imagine a problem where i needed such flexible argument list.
> can anyone provide a motivation example in ruby?
> i'd suggest to add a small sample of usage to the docs.
> -- henon

I'm not entirely sure where you'd use this sort of feature either, but
for the uninformed (such as myself)...

1. A snazzy article on Currying in Wikipedia >>
http://en.wikipedia.org/wik...
2. The "Command" design pattern >>
http://www.exciton.cs.rice.edu/JavaResources/DesignPatterns/c...

James

Ross Bamford

2/21/2006 5:41:00 PM

0

On Wed, 2006-02-22 at 02:13 +0900, henon wrote:
> cool naming, nice functionality, easy using.
> AFAIK this is a instantiation of the Design Pattern called "Command" by
> the Gang of Four.
> i can not imagine a problem where i needed such flexible argument list.
> can anyone provide a motivation example in ruby?
> i'd suggest to add a small sample of usage to the docs.
> -- henon

Oh, I never said it was _useful_ :)

Actually, I don't think there's anything in Ruby that can't be done
(better) some other way, but currying is one of those higher-order
things that every (decent) language should have ;).

Most of the examples I could contrive are in the docs - not sure if it's
linked prominently enough but did you see
http://rubymurray.rubyforge.org/files/doc/currybook...
?

James Edward Gray II also came up with a good example in the quiz
summary, based on his LazySpice spice (included in this release):

# Lazy Evaluation meets Currying...
class LazySpice < Curry::SpiceArg
def initialize( &promise )
super("LAZYSPICE")

@promise = promise
end

def spice_arg( args ) # called to provide the missing argument
[@promise.call]
end
end

logger = lambda do |time, message|
puts "[#{time.strftime('%I:%M:%S %p %m/%d/%y')}] #{message}"
end

log_now = logger.curry(LazySpice.new { Time.now })

log_now["First Message."] # => [12:47:53 PM 02/01/06] First Message.
sleep 3
log_now["Second Message."] # => [12:47:56 PM 02/01/06] Second Message.

Again, not something that's difficult to do by other means (default
argument values for example) but, well, there you go.

--
Ross Bamford - rosco@roscopeco.REMOVE.co.uk

Meinrad Recheis

2/21/2006 6:09:00 PM

0

> Oh, I never said it was _useful_ :)
in fact it is very useful for most elegantly implementing undo/redo
commands. i was just curious about other applications.

thank's for the link to the cookbook. i did only find the link to the
perl version at first.
-- Henon

Ross Bamford

2/21/2006 6:53:00 PM

0

On Wed, 2006-02-22 at 03:13 +0900, henon wrote:
> > Oh, I never said it was _useful_ :)
> in fact it is very useful for most elegantly implementing undo/redo
> commands. i was just curious about other applications.

Ahh, well, looks like I spoke too soon there.

Thanks for your kind comments :)

--
Ross Bamford - rosco@roscopeco.REMOVE.co.uk