只关心 return 值的功能合同？

Question

假设以下简单函数：

(define/contract (foo func)
  (-> (-> any/c ... any/c) #t)
  #t)

这是在尝试（但未能）表达想法 "foo takes a processor function. I don't care what arguments the processor requires (that's the caller's job) but the processor must return a singular result."

foo 的正确合同是什么？我已经完成了关于功能合同的部分；以上是我的第一个猜测，但失败了：

(foo identity)
; foo: contract violation
;   expected: a procedure that accepts 0 non-keyword arguments and arbitrarily
;     many more
;   given: #<procedure:identity>
;   identity accepts: 1 argument
;   in: the 1st argument of
;       (-> (-> any/c ... any/c) #t)
;   contract from: (function foo)
;   blaming: top-level
;    (assuming the contract is correct)
;   at: readline-input:8.18
; [,bt for context]

我也试过了，这显然不是合法的语法：

(define/contract (foo func)
  (-> (-> any any/c) #t)
  #t)
; readline-input:10:33: any: use of 'any' outside the range of an arrow
;   contract
;   in: any
; [,bt for context]

Answer 1

我想你想要unconstrained-domain->

只关心 return 值的功能合同？

contract for function that only cares about return value?

contract

racket