[Haskell-cafe] Deduce problem.

[Brandon Allbery]

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
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