T14325.hs:11:9: error:
• Could not deduce (C b (f b)) arising from a use of ‘foo’
from the context: C (f b) b
bound by the type signature for:
hm3 :: forall (f :: * -> *) b. C (f b) b => b -> f b
at T14325.hs:10:1-28
• In the expression: foo x
In an equation for ‘hm3’: hm3 x = foo x