Re: [Haskell-beginners] mayBe stuck

6 Aug 2010


      On Thu, Aug 05, 2010 at 06:20:06PM -0500, aditya siram wrote:
...
Normally yes, but here we are guaranteed to get a 'Just ...' value because
of the 'isNothing' guard.
-deech
You are correct, but that's not the point.  Every time you use
fromJust (or head, or unsafePerformIO...) you shift the burden of
proving that it is safe from the compiler onto yourself.  It's like
going to a fancy restaurant and insisting on going into the kitchen
and cooking your own meal.

-Brent
...
On Thu, Aug 5, 2010 at 5:47 PM, Brent Yorgey  wrote:
...
On Thu, Aug 05, 2010 at 05:42:40PM -0500, aditya siram wrote:
...
brS :: Maybe Int -> String -> String
brS i ss
   | isNothing i   = ss
   | otherwise     = (take (fromJust i) ss) ++ (brS newIndex newStr)
                       where
                           newIndex    = findIndex eqD newStr
                           newStr      = drop ((fromJust i) +1) ss
/me makes deech write on the blackboard 100 times, "I will not use
fromJust"
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