Return a type constraint that can be used to constrain
another typeable object to have a type related to an
array whose element type is the type of the specified
typeable. A typical usage of this is as follows:
where input and output are ports (this is the type
constraint of SequenceToArray, for example), and length
is a Variable that determines the length of the array.
has a constant value, then the resulting type
will have a length specified. If length does not have a
constant value, the the type will have an indeterminate length.