On 2006-02-16, Claus Reinke <[EMAIL PROTECTED]> wrote:
>> Oh golly. I can't live without pattern guards. they are the best darn
>> thing since sliced bread. I highly recommend them. I .. would have
>> to seriously refactor a ton of code if pattern guards disapeared.
>>
>> So much so that it would be less work to implement pattern guards for
>> other compilers and submit the patches.
>
> eh, well, pattern guards are nice. but, many of their uses are also
> easily replaced, by moving the pg-monad from the lhs to the rhs,
> and employing MonadPlus for the fall-throughs; something roughly
> like:
>
> f p1 | g1 = e1
> ..
> f pn | gn = en
> where <stuff>
>
> -->
>
> f x = fromJust $ do {p1 <- return x; guard g1; return e1}
> ..
> `mplus` do {pn <- return x; guard gn; return en}
> where <stuff>
This works, of course, but it looks far far uglier, and is harder to
type.
--
Aaron Denney
-><-
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