[racket-dev] `take' argument order

From: Eli Barzilay (eli at barzilay.org)
Date: Wed Jun 8 09:36:50 EDT 2011

So ... no objections to this?

Yesterday, Eli Barzilay wrote:
> While trying to finally get `take-while' etc, I realized that the
> problem with the `take' (and `drop' and related) argument order is
> even more thorny.  The existing problem is that `take' in lazy takes
> the number first and then the list -- not a big problem by itself,
> but:
> * Contradicts Haskell's argument order
> * Contradicts Clojure's argument order
> * *And* contradicts srfi-1's argument order for `take-while', which
>   takes the predicate first
> So how about making it take its inputs in any order?  (Possibly
> deprecating the number-last in the docs and eventually removing it.)
> No need to start a flamewar -- I know why it would be bad.  But the
> above mess and potential confusion seems big enough to outweigh it.
> Specifically, it seems to me very odd now to go with the srfi-1
> ordering for `take-while' and friends.  (I'm also fine with swapping
> the arguments completely, but it seems that the breakage makes it a
> bad change.)
> To make things balanced --
> * I see two arguments for keeping the order as it is now: (a) it makes
>   it more like `list-ref' etc, where the number comes last (potential
>   solution if the above is acceptable: make it do the same too, or
>   just admit that indexing is different from these things); and
>   (b) it accomodates better a potential future (list-slice l from too)
>   which would look odd with the from-too arguments before the list.
> * OTOH, the advantages of the number-first order are being compatible
>   with the rest of the world, and an order that is uniformly used in
>   `take-while' etc.
> Opinions?

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!

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