3 Couldn't match type ‘a’ with ‘Bool’
4 ‘a’ is a rigid type variable bound by
5 the type signature for run :: a at T8450.hs:7:15
6 Expected type: Either Bool ()
7 Actual type: Either a ()
8 Relevant bindings include run :: a (bound at T8450.hs:8:1)
9 In the second argument of ‘($)’, namely
10 ‘(undefined :: Either a ())’
11 In the expression: runEffect $ (undefined :: Either a ())
12 In an equation for ‘run’:
13 run = runEffect $ (undefined :: Either a ())