I don't think list comprehension is the solution. What you want is a map.

Would this work?

data V = A | B | C

f :: [V] -> String

f l = flip map l $ \x -> case x of

A -> 'A'

B -> 'B'

C -> 'C'

main = print $ f [A,B,C,C,A]

2014-11-09 21:58 GMT-05:00 Donn Cave <donn@avvanta.com>:

I'm guessing this isn't supported, but might be worth asking -
can I extend a list comprehension like ['A' | A <- s] to multiple values?
Like,

data V = A | B | C

pv :: [V] -> [Char]
pv [] = []
pv (A:x) = 'A':(pv x)
pv (B:x) = 'B':(pv x)
pv (_:x) = pv x

-- can that be a list comprehension, like

pv s = [
'A' | A <- s
-- ??
]

thanks,
Donn
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe

Viva Cila