Welcome to Racket v6.1.1.8.
-> (define x (lambda ([x : Int]) x))
; readline-input:1:24: Type Checker: parse error in type;
;  type name `Int' is unbound
;   in: Int
; [,bt for context]
; readline-input:1:24: Type Checker: parse error in type;
;  type name `Int' is unbound
;   in: Int
; [,bt for context]
; Type Checker: Summary: 2 errors encountered [,bt for context]
-> (define x (lambda ([x : Integer]) x))
; readline-input:2:34: Type Checker: type mismatch;
;  mismatch in filter
;   expected: ((! False @ x) | (False @ x))
;   given: (Top | Bot)
;   in: x
; [,bt for context]