GHC/Error messages
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GHC error messages and their meaning.
"Foo' is not a (visible) method of class `Bar'"
This error message occurs when one tries to instantiate a class, but did not import the functions one tries to implement.
Example:
import Prelude hiding ((==))
data Foo = Foo
instance Eq Foo where
(==) a b = True
"Cannot match a monotype with `Foo'"
See this Haskell-Cafe thread.
"Parse error in pattern"
TODO
Example: TODO