Re: [Haskell-cafe] Why does this blow the stack?

22 Dec 2007


      On 12/22/07, David Benbennick  wrote:
...
On 12/21/07, Stefan O'Rear  wrote:
...
Because they simply aren't the same.
Good point; thanks.  That means that Don's patch could theoretically
break some existing Haskell program:
In fact, it's possible to get strictness to avoid stack overflow, and
still have laziness to allow undefined:

myEnumFrom :: Integer -> [Integer]
myEnumFrom a = map (a+) $ enumDeltaIntegerStrict 0 1 where
  enumDeltaIntegerStrict x d = x `seq` x : enumDeltaIntegerStrict (x+d) d

then

*Main> (myEnumFrom 42) !! (10^6)
1000042
*Main> length $ take 10 $ myEnumFrom undefined
10