[Haskell-cafe] Language extensions

[Ilya Tsindlekht]

On Sun, May 27, 2007 at 05:34:33PM -0400, Brandon S. Allbery KF8NH wrote:
> 
> On May 27, 2007, at 17:23 , Andrew Coppin wrote:
> 
> >Personally, I try to avoid ever using list comprehensions. But  
> >every now and then I discover an expression which is apparently not  
> >expressible without them - which is odd, considering they're only  
> >"sugar"...
> 
> They are.  But they're sugar for monadic operations in the list  
> monad, so you have to use (>>=) and company to desugar them.  [x |  
> filter even x, x <- [1..10]] becomes do { x <- [1..10]; return  
> (filter even x) } becomes ([1..10] >>= return . filter even).
> 
The list monad is easily defineable in pure Haskell, so one can do 
without monadic operation as well if one wishes to.