Now argentum classes and interfaces can have parameters:
class HashMap(K, V) { ... }
interface Stream(T) { ... }Parameters can be used in place of classes in type declarations:
- in bases,
- fields,
- method parameters and results,
- inside the method bodies.
class HashMap(K, V) {
+Array(Pair(K, V)); // Base class parameterized with our class parameters
getAt(key K) ?V { ... } // Class parameters affect types of method prototypes
setAt(key K, newVal V) { ... }
forEach(visitor (K, V)) { ... } // visitor lambda is typed with class parameters.
...
}
interface Stream(T) {
get() ?T;
}
class Pair(A, B) {
a = ?A; // field `a` of type `Optional(A)` initialized with `none`
b = ?B; // Field types are also depending on class parameters.
}In v0 there are three limitations:
- Parameters can be classes and interfaces (but not value types).
- Parameters cannot be instantiated and casted to (like in Java).
- No covariance/contravariance.
Some of these limitations will be reduced in next revisions.
Arrays became generics too:
names = Array(Pair(String, Node));
x = names[0]; // x of type ?Pair(String, Node)
names[0] ? log(_.a); // If array at index 0 contains pair, print its string
connections = WeakArray(Node);These additions to the Argentum language allow to implement the standard container library and significantly reduce the amount of typecast operators.