# [Haskell-cafe] Compiler stops at SpecConstr optimization

Daniel Díaz Casanueva dhelta.diaz at gmail.com
Sun Sep 1 22:58:16 CEST 2013

```Yes, that GHC ticket shows that this problem is well known.

Thank you.

On Fri, Aug 30, 2013 at 2:19 AM, Ben Lippmeier <benl at ouroborus.net> wrote:

>
> On 30/08/2013, at 2:38 AM, Daniel Díaz Casanueva wrote:
>
> > While hacking in one of my projects, one of my modules stopped to
> compile for apparently no reason. The compiler just freezes (like if it
> where in an infinite loop) while trying to compile that particular module.
> Since I had this problem I have been trying to reduce the problem as much
> as I could, and I came out with this small piece of code:
> >
> > > module Blah (foo) where
> >
> > > import Data.Vector (Vector)
> > > import qualified Data.Vector as V
> >
> > > foo :: (a -> a) -> Vector a -> Vector a
> > > foo f = V.fromList . V.foldl (\xs x -> f x : xs) []
>
> Probably an instance of this one:
>