Literal types

[lars-reimann]

Is your feature request related to a problem? Please describe

For numbers, for examples, it should be possible to express that only a finite set of values is legal. This could be expressed by enum but that's quite cumbersome and you can no longer operate on enums like you could on, say, numbers.

Desired solution

Literal types: literal<"a", 1, true>

Open tasks

• Scoping for members. Example: On something of type literal<"a", "b">, we can access any members of String. On something of type literal<"a", 1>, we can access any members of Any. On something of type literal<"a", 1, null>, we can still access any member of Any (scoping), but must use a safe access (validation).
• Test TypeComputer.computeClassTypeForLiteralType