Copyright	(c) 2012 diagrams-core team (see LICENSE)
License	BSD-style (see LICENSE)
Maintainer	diagrams-discuss@googlegroups.com
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Monoid.Recommend

Description

A type for representing values with an additional bit saying whether the value is "just a recommendation" (to be used only if nothing better comes along) or a "committment" (to certainly be used, overriding merely recommended values), along with corresponding Semigroup and Monoid instances.

Synopsis

Documentation

data Recommend a Source

A value of type Recommend a consists of a value of type a wrapped up in one of two constructors. The Recommend constructor indicates a "non-committal recommendation"---that is, the given value should be used if no other/better values are available. The Commit constructor indicates a "commitment"---a value which should definitely be used, overriding any Recommended values.

Constructors

Recommend a
Commit a

getRecommend :: Recommend a -> a Source

Extract the value of type a wrapped in Recommend a.

(Semigroup a, Monoid a) => Monoid (Recommend a)
Semigroup a => Semigroup (Recommend a)	`Commit` overrides `Recommend`. Two values wrapped in the same constructor (both `Recommend` or both `Commit`) are combined according to the underlying `Semigroup` instance.