[Haskell-cafe] Matching constructors

[Henning Thielemann]

On Fri, 10 Feb 2006, Creighton Hogg wrote:

> Hi,
> If I have something like
> data Patootie = Pa Int | Tootie Int
> and I want to pull out the indices of all elements of a list
> that have type constructor Tootie, how would I do that?
>
> I thought I might be able to use findIndices, but I don't
> know how to express the predicate.

(\p -> case p of {Pa _ -> False; Tootie _ -> True})