Re: [Caml-list] Simple question

[Remi VANICAT <vanicat@labri.u-bordeaux.fr>]

Eric Merritt <cyberlync@yahoo.com> writes:

> let me start off by saying that if this is not the
> place to post this type of question please direct me
> to the correct list/group. I am picking up ocaml,
> starting off by doing a few simple things. I am at
> somewhat of an impass here in that I cannot figure out
> why the function below gives me type errors. It works
> fine if I leave it non-tail recursive, but as soon as
> I put in an accumulator and make it tail-recursive it
> fails to compile. If one of you could please point me
> in the right direction for solving this problem that
> would be great. btw this is only for my own
> edification. 
> 
> let rec apply_fun_list x f_list accm =
>   match f_list with
>      h::t ->
>            apply_fun_list x t accum::(h x)
>    | [] ->
>         accum::[];;

 :: is the constructor that add something at the beginning of the
list.

so you may want to say :

let rec apply_rev_fun_list x f_list accum =
  match f_list with
  | h::t ->
        apply_fun_list x t (h t)::accum
  | [] -> accum


but there, the function will reverse the list. It might not be what
you want (but List.rev is tail recursive)

by the way, I would have wrote it like :

let rec apply_fun_list x f_list =
  List.map (fun h -> h x) f_list

but List.map is not tail recursive....

-- 
Rémi Vanicat
vanicat@labri.u-bordeaux.fr
http://dept-info.labri.u-bordeaux.fr/~vanicat
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