Copyright | (c) ES Group, KTH/ICT/ES 2007-2013 |
---|---|
License | BSD-style (see the file LICENSE) |
Maintainer | forsyde-dev@ict.kth.se |
Stability | experimental |
Portability | portable |
Safe Haskell | None |
Language | Haskell98 |
The AbstExt
is used to extend existing data types with the value
'absent', which models the absence of a value.
Documentation
The data type AbstExt
has two constructors. The constructor Abst
is used to model the absence of a value, while the constructor Prst
is used to model present values.
Eq a => Eq (AbstExt a) Source # | |
Data a => Data (AbstExt a) Source # | |
Read a => Read (AbstExt a) Source # | |
Show a => Show (AbstExt a) Source # | The data type |
Lift a0 => Lift (AbstExt a0) Source # | |
The function fromAbstExt
extracts the inner value contained in AbstExt
unsafeFromAbstExt :: AbstExt a -> a Source #
Similar to fromAbstExt
, but without default value
psi :: (a -> b) -> AbstExt a -> AbstExt b Source #
The function psi
is identical to abstExtFunc
and should be used in future.
abstExtFunc :: (a -> b) -> AbstExt a -> AbstExt b Source #
The function abstExtFunc
extends a function in order to process absent extended values. If the input is ("bottom"), the output will also be ("bottom").