Compiled: Wed Dec 05 00:00:21 PST 2012 from source file: ./frege/prelude/Maybe.fr
Provides functions and instances for the Maybe type.
Compatible with the Haskell 2010 /Data.Maybe/ module.
inherited from Applicative.*>
inherited from Applicative.<*
inherited from Monad.<*>
inherited from Monad.join
inherited from Ord.<
inherited from Ord.<=
Function generated for derived istance.
inherited from Ord.>
inherited from Ord.>=
inherited from Ord.compare
inherited from Ord.max
inherited from Ord.min
The catMaybes function takes a list of Maybes and returns a list of all the Maybe.Just values.
fromMaybe d (Just a) returns a and fromMaybe d Nothing returns d
true if and only if the argument is a Maybe.Just value
true if and only if the argument is Maybe.Nothing
This function is preferrable over v == Nothing because no Eq constraint is needed.
give the first element of a list or Maybe.Nothing
The mapMaybe function is a version of map which can throw out elements. In particular, the functional argument returns something of type Maybe /b/. If this is Maybe.Nothing, no element is added on to the result list. If it just Maybe.Just /b/, then /b/ is included in the result list.
convert a Maybe to a single element list or an empty list
unJust Nothing is undefined whereas unJust (Just a) is a