[Haskell-cafe] Language extensions

[Jan-Willem Maessen]

On May 28, 2007, at 7:32 AM, Claus Reinke wrote:

>> I meant to imply more that "it's very difficult to understand why  
>> it's useful". If an extension were truely *useless*, I doubt those  
>> guys at GHC would have bothered spending years implementing them.
>>
>> Most of the documents that describe these things begin with  
>> "suppose we have this extremely complicated and difficult to  
>> understand situation... now, we want to do X, but the type system  
>> won't let us." Which makes it seem like these extensions are only  
>> useful in extremely complicated and rare situations.
>
> keep in mind that paper space is a precious and limited resource. the
> need for extensions tends to arise in practice first, but those  
> real examples
> are far too big and complex to fit into those limitations. it is  
> very difficult to
> come up with examples that are small enough to fit, yet complex  
> enough to
> exhibit the problem. which means that the examples usually look  
> artificial,
> but small and complete, or realistic, but so large that their  
> presentation
> has to be shallow enough to border on vague.

But I do wonder if we shouldn't declare a moratorium on examples that  
involve interpreters for simply-typed languages (which tend to  
characterize none of the problems I'm actually trying to solve---and  
that includes fiddling with non-simply-typed languages of a similar  
sort) in favor of examples which actually perform some sort of a  
useful manipulation.

This is why I absolutely LOVE functional pearls of all sorts, by the  
way.

-Jan-Willem Maessen


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