Data.Agreement

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"

Documentation

data Agreement a

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

Functor Agreement

Defined in Data.Agreement

Methods

fmap :: (a -> b) -> Agreement a -> Agreement b

(<$) :: a -> Agreement b -> Agreement a

Eq a => Monoid (Agreement a)

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)

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

This picks out consistent choices as Just.