ForSyDe-3.0: ForSyDe's Haskell-embedded Domain Specific Language. Source code Contents Index

ForSyDe.Shallow.AbsentExt Portability portable Stability experimental Maintainer forsyde-dev@ict.kth.se

Description

The AbstExt is used to extend existing data types with the value 'absent', which models the absence of a value.

Synopsis

data AbstExt a = Abst | Prst a fromAbstExt :: a -> AbstExt a -> a abstExt :: a -> AbstExt a psi :: (a -> b) -> AbstExt a -> AbstExt b isAbsent :: AbstExt a -> Bool isPresent :: AbstExt a -> Bool abstExtFunc :: (a -> b) -> AbstExt a -> AbstExt b

Documentation

data AbstExt a Source

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. Constructors Abst Prst a Instances Eq a => Eq (AbstExt a) Read a => Read (AbstExt a) Show a => Show (AbstExt a)

fromAbstExt :: a -> AbstExt a -> a Source

The function fromAbstExt converts a value from a extended value.

abstExt :: a -> AbstExt a Source

The function abstExt converts a usual value to a present value.

psi :: (a -> b) -> AbstExt a -> AbstExt b Source

The function psi is identical to abstExtFunc and should be used in future.

isAbsent :: AbstExt a -> Bool Source

The functions isAbsent checks for the absence of a value.

isPresent :: AbstExt a -> Bool Source

The functions isPresent checks for the presence of a value.

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").

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