Hi,
After a lot of thinking, I can't get what I
am doing wrong in this code:
------
data ( RandomGen g ) => RandomMonad g a = RandomMonad (g -> a)
instance Monad (RandomMonad g) where
return = RandomMonad . const
RandomMonad f1 >>= f2 = RandomMonad f3 where
f3 a = f2f1 a (next a)
RandomMonad f2f1 = f2 . f1
------
I get this error message:
Could not deduce (RandomGen g)
from the context (Monad (RandomMonad g))
arising from a use of `RandomMonad' at src/encherDB.hs:10:11-21
Possible fix:
add (RandomGen g) to the context of the type signature for `return'
In the first argument of `(.)', namely `RandomMonad'
In the expression: RandomMonad . const
In the definition of `return': return = RandomMonad . const
but I'm not smart enough to understand what
it means.
Thanks a lot,
Maurício
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