VariantΒΆ
Variant
is a sum type, i.e. a wrapper for a value which can be of different
types. For instance in the following code x
is a variant whose value can be
an Int
, a Float
or a String
:
import Haskus.Utils.Variant
x :: V '[Int,Float,String]
We use a type-level list of types to statically constrain the possible value
types. Compared to usual sum types (e.g. Either Int Float
) it allows us to
have variants which can contain any number of types and to manipulate
(extend/filter/etc.) the list in a type-safe way and without requiring new data
types.
See also