Parameterized Types

Claro supports the definition of types that may be parameterized with a generic type so that they can be used to contain arbitrary types. For example the following is a definition of a type Maybe<T> that has the generic type param T:

Fig 1:

newtype Maybe<T> : oneof<T, std::Error<std::Nothing>>

This type definition is useful for describing the generic concept of a value that may or may not be present, without needing to define repeated declarations for each specific type that may or may not be present:

Note: Claro's error messaging is a work in progress - the below error message will be improved.

Fig 2:

var maybeInt: Maybe<int> = Maybe(10);
print(maybeInt);

var maybeStr = Maybe("hi");
print(maybeStr);

Output:

Maybe(10)
Maybe(hi)

Generic Type Param Must be Referenced in Type Declaration

Fig 3:

newtype Invalid<X> : struct {row: int, col: int}

Compilation Errors:

Warning! The following declared symbols are unused! [X]
1 Error