On 30 Jan 2008, at 7:19 PM, Anton van Straaten wrote:
Derek Elkins wrote:
On Thu, 2008-01-31 at 02:18 +0000, Neil Mitchell wrote:
...
It isn't something that would throw a C programmer off, but it is
something that could confuse a pure Haskell programmer. And the only
way I could be sure of radians versus degrees was by trying it out,
not a great strategy for determining the implementation of
functions!
Uh, why not? Often that's exactly what I do as checking even
conveniently located documentation is more time consuming than just
trying it.
I agree, but at the risk of veering uncharacteristically off-topic
for haskell-cafe, I think it's an interesting example of the degree
of assurance about correctness we're willing to accept in practice,
in real development.
We discover a function called, say, "cos", probably by guessing
it's name, run a very small number of simple tests on it, see the
answers we expect, and decide that it's the function we want.
True enough; more complicated tests seem to reveal the opposite
conclusion:
> quickCheck $ \ x -> cos (x + 2*pi) == cos x
Falsifiable, after 2 tests:
-1.0
jcc
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