analysis

Klar Analysis / Type Checker

Grammar

In compatibility.go, you'll see syntax in comments that describe typing properties.

• A => B means type A is assignable to B.
• Uppercase letters are type variables. A => A refers to the same type on both sides.
• Lowercase letters are variables (not types). Types can be assigned to them using the syntax a: T, meaning variable a has type T.
• Klar type syntax is also used, so [A] is a list, and A | B is a union type.
• if, and and or are also used. A => B | C if A => B or A => C means type A is compatible with the union of B and C, if A is assignable to either B or C.
• A =!> B means type A is not assignable to B.
• A = B means type A is equal to B (similar meaning for !=).
• A <=> B means type A is assignable to B and vice versa.

Overload Resolution

Overload Declaration Rules

Variadics

Either all or no overloads must have variadic positional parameters.

Not allowed	Not allowed
func(...Int) func(Int, Int)	func(String, ...Int) func(...String | Int) func(String, Int)

Compatibility

Allowed (interface/tag)	Not allowed (union)
type #Vehicle type Car {} func(Vehicle) func(Car)	func(A | B) func(A)

Optionals

Not allowed	Not allowed
func(Int?) func(Int)	func(String, Int, Bool) func(String, Int?, Bool)