List to tuples

[WJ]

Frode Vatvedt Fjeld wrote:

> > say there's a list of even length
> > (a b c d e f ......)
> >
> > how do i turn this into
> > ((a b) (c d) (e f)....)
>
> The mapping idiom doesn't work so well here, since that's all about
> transforming each element individually, whereas here you process
> elements two by two (or the list as such in steps of two).
>
> I think this is the most natural solution in Common Lisp:
>
> (loop for (x y) on list by #'cddr collect (list x y))

OCaml:

let list = ["a";"b";"c";"d"];;

let rec g=function x::y::z->(x,y)::g z | _->[]
in g list;;

[("a", "b"); ("c", "d")]

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