.x: Int
.f: Int -> Int

.C: ClassType
# or .C.__call__: Int -> .C
.C.__call__: (x: Int) -> .C
.C.f: (self: .C, y: Int) -> Int

#[
# Class declaration syntax
.C: ClassType {.x = Int}
.C.
    __call__: (x: Int) -> .C
    f: (self: .C, y: Int) -> Int
]#