Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Agreement

Description

A simple data structure helping us ask questions of the following sort: "does all this data have the same BLANK and if so what is it?"

For example: > doTheseHaveTheSameLength :: [String] -> String > doTheseHaveTheSameLength l = case foldMap (Somebody . length) of > Somebody n -> "They all have length " <> show n > Nobody -> "The lengths differ" > Anybody -> "You didn't give me any strings"

Synopsis

data Agreement a
- = Anybody
- | Somebody a
- | Nobody
getSomebody :: Agreement a -> Maybe a

Documentation

data Agreement a Source #

We have the following constructors: * Somebody is a consistent choice of an element. * Nobody is an inconsistent choice. * Anybody is a failure to make any choice.

Constructors

Anybody
Somebody a
Nobody

Instances

Instances details

Functor Agreement Source #
Instance details Defined in Data.Agreement Methods fmap :: (a -> b) -> Agreement a -> Agreement b # (<$) :: a -> Agreement b -> Agreement a #
Eq a => Monoid (Agreement a) Source #
Instance details Defined in Data.Agreement Methods mempty :: Agreement a # mappend :: Agreement a -> Agreement a -> Agreement a # mconcat :: [Agreement a] -> Agreement a #
Eq a => Semigroup (Agreement a) Source #
Instance details Defined in Data.Agreement Methods (<>) :: Agreement a -> Agreement a -> Agreement a # sconcat :: NonEmpty (Agreement a) -> Agreement a # stimes :: Integral b => b -> Agreement a -> Agreement a #

getSomebody :: Agreement a -> Maybe a Source #

This picks out consistent choices as Just.