On Wed, 2010-04-14 at 12:16 -0700, Ashley Yakeley wrote: > On 2010-04-14 11:12, John Meacham wrote: > > On Wed, Apr 14, 2010 at 02:07:52AM -0700, Ashley Yakeley wrote: > >>> So the facts that > >>> (1) f == g > >>> (2) f undefined = 6 > >>> (3) g undefined = undefined > >>> is not a problem? > >> > >> This is not a problem. f and g represent the same moral function, > they > >> are just implemented differently. f is smart enough to know that > its > >> argument doesn't matter, so it doesn't need to evaluate it. g waits > >> forever trying to evaluate its function, not knowing it doesn't > need it. > > > > Hence they are distinct functions, > > They are distinct Haskell functions, but they represent the same > moral > function. >
Are
f 0 = 1
f n = f (n - 1) + f (n - 2)
and
g 0 = 1
g n | n > 0 = g (n - 1) + g (n - 2)
| n < 0 = g (n + 2) - g (n + 1)
The same (morally) function?
Are:
f x = 2*x
and
f x = undefined
The same function
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