Types are associated at a fundamental level with the set of elements that the type contains. Type expressions can occur only as part of the definition of channels or other types, but the name of a type can be used anywhere that a set is required.
For example, the type of integer values is Int and the type of
boolean values is Bool, so
{0..3} <= Int
{true, false} == Bool
In type expressions the tuple syntax denotes a product type and the dot operation denotes a composite type so that
({0,1},{2,3})denotes{(0,2),(0,3),(1,2),(1,3)}
{0,1}.{2,3}denotes{0.2, 0.3, 1.2, 1.3}
The Set and Seq functions which return the powerset and
sequence-space of their arguments are also useful in type expressions.
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