61 lines
1.7 KiB
Racket
61 lines
1.7 KiB
Racket
#lang scheme
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(require htdp/error)
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;
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;
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;
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; ;;; ;;;
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; ; ; ; ;
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; ; ; ;
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; ; ; ; ;;;; ; ; ; ; ; ;
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; ;;; ; ; ; ; ;;;;; ; ; ; ;
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; ; ; ; ; ; ; ; ; ; ;
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; ; ; ; ; ; ; ; ; ; ;
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; ; ; ; ; ; ; ; ; ; ;; ; ;
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; ;;; ;;;; ; ; ; ; ;; ; ; ;
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; ;
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; ; ;
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; ;;;
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(provide nat> nat? proc> bool> num> ip> string> symbol>)
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;; Any -> Boolean
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(define (nat? x)
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(and (number? x) (integer? x) (>= x 0)))
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;; Symbol X -> X
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(define (bool> tag x)
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(check-arg tag (boolean? x) "boolean" "first" x)
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x)
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;; Symbol X -> X
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(define (string> tag x)
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(check-arg tag (string? x) "string" "first" x)
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x)
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(define ip> string>)
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;; Symbol X -> X
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(define (symbol> tag x)
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(check-arg tag (symbol? x) "symbol" "second" x)
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x)
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;; Symbol X Nat -> X
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(define (proc> tag f ar)
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(check-proc tag f ar "first"
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(if (> ar 1)
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(format "~a arguments" ar)
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"one argument"))
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f)
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;; Symbol X (Number -> Boolean) String String -> X
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(define (num> tag x pred? spec which)
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(check-arg tag (and (number? x) (pred? x)) spec which x)
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x)
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;; Symbol X String -> X
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(define (nat> tag x spec)
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(check-arg tag (nat? x) spec "natural number" x)
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x)
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