Racket 强制执行函数的输入类型
Racket enforce input types for function
我想强制输入球拍中函数的数据类型。例如,在此函数中,我希望得到整数并在有人输入字符串时抛出错误。
在 Racket 中是否有标准的方法来强制执行此操作?
(sum-coins pennies nickels dimes quarters)
pennies : integer?
nickels : integer?
dimes : integer?
quarters : integer?
是的,有两种标准方法。
合同
Contracts 检查条件并在运行时引发错误:
#lang racket
(define/contract (sum-coins pennies nickels dimes quarters)
(-> integer? integer? integer? integer? integer?)
(+ (* 1 pennies)
(* 5 nickels)
(* 10 dimes)
(* 25 quarters)))
(sum-coins 1 2 3 4)
;; => 141
(sum-coins "1" 2 3 4)
; sum-coins: contract violation
; expected: integer?
; given: "1"
; in: the 1st argument of
; (->
; integer?
; integer?
; integer?
; integer?
; integer?)
; contract from: (function sum-coins)
; blaming: /tmp/so.rkt
; (assuming the contract is correct)
; at: /tmp/so.rkt:3.18
; Context (errortrace):
; /tmp/so.rkt:11:0: (sum-coins "1" 2 3 4)
; /tmp/so.rkt:11:0: (sum-coins "1" 2 3 4)
打字球拍
或者您可以使用 Typed Racket,它会在编译时检查类型:
#lang typed/racket
(define (sum-coins [pennies : Integer]
[nickels : Integer]
[dimes : Integer]
[quarters : Integer])
(+ (* 1 pennies)
(* 5 nickels)
(* 10 dimes)
(* 25 quarters)))
(sum-coins 1 2 3 4)
;; => 141
(sum-coins "1" 2 3 4)
; /tmp/so2.rkt:14:11: Type Checker: type mismatch
; expected: Integer
; given: String
; in: "1"
我想强制输入球拍中函数的数据类型。例如,在此函数中,我希望得到整数并在有人输入字符串时抛出错误。
在 Racket 中是否有标准的方法来强制执行此操作?
(sum-coins pennies nickels dimes quarters)
pennies : integer?
nickels : integer?
dimes : integer?
quarters : integer?
是的,有两种标准方法。
合同
Contracts 检查条件并在运行时引发错误:
#lang racket
(define/contract (sum-coins pennies nickels dimes quarters)
(-> integer? integer? integer? integer? integer?)
(+ (* 1 pennies)
(* 5 nickels)
(* 10 dimes)
(* 25 quarters)))
(sum-coins 1 2 3 4)
;; => 141
(sum-coins "1" 2 3 4)
; sum-coins: contract violation
; expected: integer?
; given: "1"
; in: the 1st argument of
; (->
; integer?
; integer?
; integer?
; integer?
; integer?)
; contract from: (function sum-coins)
; blaming: /tmp/so.rkt
; (assuming the contract is correct)
; at: /tmp/so.rkt:3.18
; Context (errortrace):
; /tmp/so.rkt:11:0: (sum-coins "1" 2 3 4)
; /tmp/so.rkt:11:0: (sum-coins "1" 2 3 4)
打字球拍
或者您可以使用 Typed Racket,它会在编译时检查类型:
#lang typed/racket
(define (sum-coins [pennies : Integer]
[nickels : Integer]
[dimes : Integer]
[quarters : Integer])
(+ (* 1 pennies)
(* 5 nickels)
(* 10 dimes)
(* 25 quarters)))
(sum-coins 1 2 3 4)
;; => 141
(sum-coins "1" 2 3 4)
; /tmp/so2.rkt:14:11: Type Checker: type mismatch
; expected: Integer
; given: String
; in: "1"