[Haskell] Mixing monadic and non-monadic functions

[Iavor S. Diatchki]

hi,
at some level you are right that some more syntactic sugar
and stuff could make monads more atracitve. for the time
being here is how i'd write what you want bellow:

f # m           = liftM f m
mx === my  = liftM2 (==) m1 m2

assertBool "fail" $ (length # someFunc a) === (length # someFunc b)

at the moment we only have syntactic sugar for working with the list monad
(list comprehensions etc), and environemnt (aka reader) monad (implicit 
parameters).

hope this helps
-iavor

Sean E. Russell wrote:

>Hello,
>
>I posted this question to comp.lang.functional, and someone suggested that I 
>try this group instead.
>
>I'm struggling with monads.  Well, not monads themselves, but mixing them with 
>non-monadic functions.
>
>Here's my base case:
>
>	someFunc :: String -> IO [a]
>	...
>		ax <- someFunc a
>		bx <- someFunc b
>		assertBool "fail" $ length ax == length bx
>
>I don't like the assignments; the typing is redundant, if I have a lot of 
>asserts like this, and the "variables" are temporary.  What I'd much rather 
>have is:
>
>	...
>		assertBool "fail" $ (length $ someFunc a) == (length $ someFunc b)
>
>which is more readable, to my eye.
>
>The only solution which has been suggested that may work is liberal use of the 
>liftM variants, but this gets *really* tedious and obtuse.
>
>Is there an elegant way to do what I want to do, or am I stuck with 
>procedural-style assignments and bunches of temp vars?
>
>Thanks!
>
>  
>