Revision history for commutative-semigroups

0.1.0.0 -- 2022-06-12

• Commutative (Product a) now requires CommutativeProduct a. CommutativeProduct is a new class to indicate (*) from Num is commutative, which is not required by Num. (Example: multiplication on quaternions is non-commutative, and the Quaternion a type from the linear package has a valid instance RealFloat a => Num (Quaternion a).)

  Remark: There is also no canonical subclass class in the Num hierarchy which implies commutative (*), as both Integral and Floating instances work here:

  • Integral instances are customarily Euclidean Domains, which are commutative rings with extra conditions.

  • Floating instances customarily expect (+), (*), and exp to form an exponential field, which is also a commutative ring with extra conditions.

0.0.2.0 -- 2022-03-26

• Add instance Ord a => Commutative (Set a)
• Add instance Commutative IntSet

0.0.1.0 -- 2021-01-28

• Add instance for Maybe.

0.0.0.0 -- 2021-01-06

Initial version, created from groups package.