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Re: Isn't that nice?

by John M. Dlugosz (Monsignor)
on Aug 30, 2002 at 13:57 UTC ( #194110=note: print w/replies, xml ) Need Help??

in reply to Isn't that nice?

enhancements that are entirely new to any language: dedicated applications of functions by making a parameter constant,

What's that?


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Re: Re: Isn't that nice?
by jepri (Parson) on Aug 30, 2002 at 14:37 UTC
    I'm not sure, but maybe prebinding parameters?

    I didn't believe in evil until I dated it.

      Forgive the duff syntax, been busy and I can't find an example, I'd have thought the lecture notes would be available online somewhere.., and I can't recall all the details precisely.

      sub divide( $x, $y ) { $x / $y } sub half assuming divide( $y=2 )
      Uh does that look familiar to anyone?


      Brother Frankus.

        Probably more like:
        my &half := &divide.assuming( $y => 2 )
        But that's the general idea.


        It's just currying. The syntax is unique to perl, but the semantics are reasonably common in functional programming languages. The 'new' thing about perl 6's 'assuming' operator is that, according to Damian, it doesn't actually create a new function, but that's not really going to be user visible.

        Yes, it looks a little bit like OCaml (i.e. I'm not sure this has never been seen in any other language). :-)

        # let divide ~x ~y = x / y;; val divide : x:int -> y:int -> int = <fun> # let half = divide ~y:2;; val half : x:int -> int = <fun> # half 120;; - : int = 60

        The mutant offspring of COBOL and ML? You want me to be *familiar* with something like that?!
        Is that really going to be in Perl 6 like that?

        How is that an improvement over sub half { divide($_[0]/2) };? Especially when you consider that to write sub half assuming... as shown you have (apparently) to know that divide has a $y to which to assign 2.

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