[Haskell-cafe] Combining State and List Monads

Henry Laxen nadine.and.henry at pobox.com
Sat Aug 25 06:35:37 CEST 2012

Dear Cafe,

It seems to me there should be some simple way of doing this, but thus
far it eludes me.  I am trying to combine the State and List monads to
do the following:

countCalls = do
  a <- [1..2]
  b <- [1..2]
  modify (+1)
  return (a,b)

where with some combination of ListT, StateT, List, State, or who
knows what would result in:


assuming we initialize the state to 0

Is there any way to make this happen?
Thanks in advance.

Henry Laxen

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