Antoine Latter wrote:
> On Sat, Jun 20, 2009 at 1:05 PM, Deniz Dogan<[email protected]> wrote:
>> I (too) often find myself writing code such as this:
>>
>> if something
>> then putStrLn "howdy there!"
>> else if somethingElse
>> then putStrLn "howdy ho!"
>> else ...
>>
>> I recall reading some tutorial about how you can use the Maybe monad
>> if your code starts looking like this, but as you can see, that
>> doesn't really apply here. "something" and "somethingElse" are simply
>> booleans and each of them have different actions to take if either of
>> them is True.
>>
>> So how do I make code like this prettier?
>
> I'm not entirely sure if this is haskell'98, but GHC seems to support
> this sort of layout:
>
> main = do
> <some computation>
>
> if something then someOtherComputation else do
>
> <continue at the same indentation>
> <<<<<
IMHO, this is ugly and counterintuitive; I like having a single "point
of exit" (to use an imperative programming term) of a function. Your
suggestion is equivalent to
someComputation;
if something then begin
someOtherComputation;
exit;
end;
more;
in, say, Pascal. This obscures the fact that "more;" is sometimes/often
not executed. (You could argue the same about exceptions, but they are a
necessary evil ;-).
Regards,
--
Jochem Berndsen | [email protected]
GPG: 0xE6FABFAB
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