[Haskell-cafe] Deduce problem.

Brandon Allbery allbery.b at gmail.com
Thu Nov 17 06:17:34 CET 2011

On Wed, Nov 16, 2011 at 23:54, Magicloud Magiclouds <
magicloud.magiclouds at gmail.com> wrote:

> I think this is where I did not understand from the very beginning.
> If the the declaration was correct, then why cannot b be H?
> Referring to Data.List.genericLength, I was confused.

Because it doesn't mean that *you* get to decide what it is; it means *the
caller* gets to decide, and you are obligated to honor the caller's wishes.
 Returning always an H violates this, because there is no way to prove that
H is the only possible response.

brandon s allbery                                      allbery.b at gmail.com
wandering unix systems administrator (available)     (412) 475-9364 vm/sms
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20111117/a0399446/attachment.htm>

More information about the Haskell-Cafe mailing list