currying

currying

[Eric J. Van der Velden]

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Hello,

1.

I have curried (compose) so that I can define (not2) below,

(define compose(lambda(f)
        (lambda(g)
                (lambda(x)
                        (f(g x))))))

(define not2
        (compose not)
)

((not2 null?)'())

This is OK.

2.

I do this also,

(define both(lambda(f)
        (lambda(a b)
                (and(f a)(f b))
        )
))

(define neithernull
        (both ((compose not)null?) )
)

(neither '()'())

This is OK.

3.

But both here below are ERR,

(define neither
        (both ((compose not)) )

(define neither
        (both (compose not))

The first one doesn't compile. The second one does, but this is not what I
meant; It suspects two arguments, the '() '() for example , instead of one,
the funtion null? for example.

Can I define (neither) is some way that I can do something like

        ((neither null?)'(a)'(a))

Thanks,

Eric J.

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Re: currying

[Thien-Thi Nguyen]

() "Eric J. Van der Velden" <ericjvandervelden@gmail.com>
() Mon, 6 Sep 2010 21:36:58 +0200

   (define neither
     (both (compose not))

   The first one doesn't compile. The second one does, but this is
   not what I meant; It suspects two arguments, the '() '() for
   example, instead of one, the funtion null? for example.

   Can I define (neither) is some way that I can do something like

   ((neither null?)'(a)'(a))

Presuming that you'd like this expression to have value #t, try:

(define neither
  (lambda (p?)
    (both ((compose not) p?))))

aka

(define (neither p?)
  (both ((compose not) p?)))

Style nit: i somewhat dislike the one-arg ‘compose’.  IMHO, the
procedure most befitting that name should take any number of args,
including zero.  That complicates the implementation, but such is
life on the edge of the knife...

Re: currying

[Andy Wingo]

Hi Eric,

Your code is not formatted idiomatically. If you want feedback, use
standard style.

Lacking anything Guile-specific, I think Taylor Campbell's style guide
is as fine as any:

  http://mumble.net/~campbell/scheme/style.txt

Cheers,

Andy
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