Difference between revisions of "GHC/Error messages"
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("Cannot match a monotype with `Foo'") |
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GHC error messages and their meaning. |
GHC error messages and their meaning. |
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== "Foo' is not a (visible) method of class `Bar'" == |
== "Foo' is not a (visible) method of class `Bar'" == |
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(==) a b = True |
(==) a b = True |
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</haskell> |
</haskell> |
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+ | == "Cannot match a monotype with `Foo'" == |
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+ | See [http://www.haskell.org/pipermail/haskell-cafe/2009-October/067806.html this] Haskell-Cafe thread. |
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Revision as of 06:20, 15 October 2009
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