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Paste # 89636
2014-09-30 14:12:22

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  1. #lang typed/racket
  2.  
  3. (define: (parse [xs : (Rec A (Listof (U Symbol A)))]) : (Listof String)
  4.   (map (lambda: ([item : (Rec B (U Symbol B))])
  5.          "Hello, world") xs))

=>

eval:2:0: Type Checker: Error in macro expansion -- parse

error in type;

 recursive types are not allowed directly inside their

definition

  in: (Rec B (U Symbol B))