[Haskell-cafe] Function composition in run-time?

[Iustin Pop]

On Wed, Aug 24, 2011 at 04:57:19PM +0400, dokondr wrote:
> On Wed, Aug 24, 2011 at 4:44 PM, Iustin Pop <iustin at google.com> wrote:
> 
> > On Wed, Aug 24, 2011 at 04:35:42PM +0400, dokondr wrote:
> > > Hi,
> > > What is the Haskell way to compose functions in run-time?
> > > Depending on configuration parameters I need to be able to compose
> > function
> > > in several ways without recompilation.
> >
> >
> A simple alternative to if would be:
> >
> >  options = [ ("foo", f1 . f2 . f3)
> >            , ("bar", f1 . f3 )]
> >
> > and then "lookup param options". I don't know if this is what you're
> > looking for, though.
> >
> >
> Thanks!
> Yes, this is what I need - simple and easy. Yet, how function application
> will work in this case ?
> I mean after lookup returns me a composition ... need to check what type
> will it be.

Well, as with your 'if', all compositions must have the same type, since
lists are homogeneous.

regards,
iustin