Re: [Haskell-beginners] Question re "Pattern match(es) are non-exhaustive"

On 2015-02-10 18:01, Kim-Ee Yeoh wrote:

On Tue, Feb 10, 2015 at 11:14 PM, Frerich Raabe wrote:

...

I noticed that a similiar case exists with

f :: Bool -> Bool f x | x = True | not x = False

[..]

Now you could point out that "Ah, but look at the definition of not. It could inline, simplify, et voila, obtain

f True = True f False = False

and hence pattern-matching is complete."

Therein lies the rub. All that inlining and simplification boils down to evaluating the program _in_ the compiler, so if your program diverges so would the compiler, which wouldn't be a happy thing.

Ah, true. The compiler would need to evaluate the program, I didn't realize that. But: what do you mean by 'if your program diverges' -- diverges from what? -- Frerich Raabe - raabe@froglogic.com www.froglogic.com - Multi-Platform GUI Testing