Type tests and conversions
Scheme defines a number of standard type testing predicates.
For example (vector? x) is #t if and only if
x is a vector.
Kawa generalizes this to arbitrary type names:
If T is a type-name (that is in scope at compile-time),
then T?#t if the argument is an instance of the type T#f otherwise:
(gnu.lists.FVector? #(123)) ⇒ #t
(let ((iarr (int[] 10))) (int[]? iarr)) ⇒ #t
In general:
(T? x) ⇒ (instance? x T)
Procedure: instance? value type
Returns #t iff value is an instance of type type.
(Undefined if type is a primitive type, such as int.)
Procedure: as type value
Converts or coerces value to a value of type type.
Throws an exception if that cannot be done.
Not supported for type to be a primitive type such as <int>.
