I am becoming extremely frustrated now. The task I want to perform is
simple, yet I simply cannot make Haskell do what I want.
I've given up hope of ever getting my program to handle infinite result
sets. That means I can make do with just ListT. So I have the following
monad:
type MyMonad x = StateT MyState (ListT Identity) x
Now I'm trying to run two computations, starting from _the same state_,
and combine the two resulting lists. The trouble is, I am literally
losing the will to live trying to comprehend the whinings of the type
checker. The operation I'm trying to perform is perfectly simple; I
don't understand why this has to be so damned *difficult*! >_<
Any suggestions?
I found that by using the brief and easily memorable construction
"runIdentity $ runListT $ runStateT foo state" I can get at the result
set for each action, and combine them. But nothing in hell seems to
transform this from [((), MyState)] back into MyMonad ().
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