discriminated union


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discriminated union

(theory)
The discriminated union of two sets A and B is

A + B = inA, a) | a in U inB, b)| b in

where inA and inB are arbitrary tags which specify which summand an element originates from.

A type (especially an algebraic data type) might be described as a discriminated union if it is a sum type whose objects consist of a tag to say which part of the union they belong to and a value of the corresponding type.
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Another user @raboof noted, "Pleasantly surprised to see Apple's #swift embracing discriminated unions http://goo.gl/i70O2U & pattern matching http://goo.gl/Aoyj87."
Pleasantly surprised to see Apple's (https://twitter.com/search?q=%23swift&src=hash) #swift embracing discriminated unions (http://t.co/ewtI471KXq) http://t.co/ewtI471KXq & pattern matching (http://t.co/PUr6Ktci7a) http://t.co/PUr6Ktci7a - Atif Aziz (@raboof) (https://twitter.com/raboof/statuses/473867284810063872) June 3, 2014
Those new to F# will learn how to use currying, partial application, and delegation; streamline type creation and safety with record types and discriminated unions; the role of collection types and modules for handling data sets effectively; the use of pattern matching to decompose complex types; make software more responsive; and a great deal more.