Nice :)
On Sunday, December 9, 2012 1:17:48 AM UTC+1, Michał Marczyk wrote:
>
> Better yet,
>
> (defmacro iff [test & {:keys [then else]}]
> `(if ~test ~then ~else))
>
> (that's doing the lookup for then and else in the map constructing
> from the macro's rest argument at compilation time rather than in an
> evaluated map including both at run time).
>
> Cheers,
> Michał
>
>
> On 9 December 2012 00:40, Ben Wolfson <[email protected] <javascript:>>
> wrote:
> > You may want to use some delays to prevent evaluation of untaken
> branches:
> >
> > user=> (iff true :else (println 1) :then (println 3))
> > 3
> > 1
> > nil
> > user=>
> >
> >
> > On Sat, Dec 8, 2012 at 3:02 PM, Thomas Goossens
> > <[email protected] <javascript:>> wrote:
> >> One of the issues i had and still have with the if function is that
> >> because it has ordered arguments, makes things more complex.
> >>
> >> For small functions this is no so much of a problem.
> >> (if test 1 0)
> >>
> >> But when things get larger, that extra complexity of order without
> explicit
> >> information can get significant, I believe
> >>
> >> So I wanted (this would be officially my first macro ever!) something
> that
> >> behaved as follows:
> >>
> >> (if test
> >> :then true
> >> :else false)
> >>
> >> (if test
> >> :else false
> >> :then true)
> >>
> >> Which is what I eventually did:
> >>
> >> (defmacro iff
> >> [test & body]
> >> (let [args (apply hash-map body)]
> >> `(if ~test (:then ~args) (:else ~args))))
> >>
> >> Any thoughts, improvements on my macro? (Also I'm not quite sure how to
> >> document my macro. So any advice on that is appreciated :)
> >>
> >>
> >>
> >> --
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> >
> >
> >
> > --
> > Ben Wolfson
> > "Human kind has used its intelligence to vary the flavour of drinks,
> > which may be sweet, aromatic, fermented or spirit-based. ... Family
> > and social life also offer numerous other occasions to consume drinks
> > for pleasure." [Larousse, "Drink" entry]
> >
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