Personal tools

GHC/Error messages

From HaskellWiki

< GHC(Difference between revisions)
Jump to: navigation, search
("Foo' is not a (visible) method of class `Bar'")
m ("Foo' is not a (visible) method of class `Bar'")
Line 14: Line 14:
 
Example:
 
Example:
 
<haskell>
 
<haskell>
import Prelude hiding ((==))
+
import Prelude hiding ((==))
data Foo = Foo
+
  +
data Foo = Foo
  +
 
instance Eq Foo where
 
instance Eq Foo where
 
(==) a b = True
 
(==) a b = True

Revision as of 17:07, 9 October 2009

GHC error messages and their meaning.

1 "Parse error in pattern"

TODO

Example: TODO


2 "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