[Haskell-cafe] Monadic Composition

[Tomasz Zielonka]

On Wed, May 12, 2004 at 01:33:40AM +0100, Jorge Adriano Aires wrote:
> This higher order function seems quite useful to me and not trivial, so I  
> expected it to be available. When this happens I wonder if I'm missing 
> something. Am I complicating things? Is it actually available (or some other 
> that does the trick) ? Or is it just me who finds this usefull enough to be in 
> the libs?

I've used such a function at least once, in context of processing
program options (search for foldl in
http://www.haskell.org/pipermail/haskell/2004-January/013412.html).

So, yes, it is useful, but should it be included in a standard Monad
module? After all, this module contains mostly trivial functions ;)

BTW. You can write this function using foldM:
    
    compM l a = foldM (#) a l

where # is an often used reverse application operator:

    x # f = f x

Best regards,
Tom

-- 
.signature: Too many levels of symbolic links