[Haskell-cafe] Signature for non-empty filter

[Henning Thielemann]

On Thu, 7 Feb 2008, Bulat Ziganshin wrote:

> Thursday, February 7, 2008, 4:04:03 AM, you wrote:
>
> > I.e., it's not necessary to restrict the class of functions you consider
> > if you're willing to give up on full automation.  So I disagree with the
> > "only if" below.
>
> ok, read this as "computer can ensure...", because it was exactly the
> original question - "can computer check that any given function in
> turing-complete language is non-trivial?"

My original question according to
 http://www.haskell.org/pipermail/haskell-cafe/2008-February/039161.html
  was "Is Haskell's type system including extensions strong enough for
describing a function, that does not always return a trivial value?"