[Haskell-cafe] Very crazy
andrewcoppin at btinternet.com
Tue Sep 25 06:09:52 EDT 2007
Brandon S. Allbery KF8NH wrote:
> On Sep 25, 2007, at 5:56 , Andrew Coppin wrote:
>> More seriously, I have no idea how you'd implement this in Haskell.
>> Presumably the standard show instance for Int, Double, etc. is in
>> native C? You could probably reimplement it in Haskell for the
>> integer case, but not for floating-point...
> Actually, Text.Printf is pure Haskell. (Very *scary* Haskell: deep
> type hackery is needed to make it work. Don't try to understand
> PrintfType. :)
Forget PrintfType - I can't even understand the haddoc page yet!
(printf performs I/O, yet it is outside the I/O monad. It seems to
accept an arbitrary number of arguments, which is obviously impossible.
It's *almost* as scary as the original. Although the original will crash
your program is you use it wr... oh, so does this one. Cool.)
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