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sugar/coercion/contracts.rkt

47 lines
1.1 KiB
Racket

11 years ago
#lang racket/base
(require racket/contract "../define/provide.rkt" "values.rkt")
(define-syntax-rule (make-blame-handler try-proc expected-sym)
(λ(b)
(λ(x)
(with-handlers ([exn:fail? (λ(e)
(raise-blame-error
b x
'(expected: "~a" given: "~e")
expected-sym x))])
(try-proc x)))))
(define+provide coerce/integer?
(make-contract
#:name 'coerce/integer?
#:projection (make-blame-handler ->int 'can-be-integer?)))
(define+provide coerce/string?
(make-contract
#:name 'coerce/string?
#:projection (make-blame-handler ->string 'can-be-string?)))
(define+provide coerce/symbol?
(make-contract
#:name 'coerce/symbol?
#:projection (make-blame-handler ->symbol 'can-be-symbol?)))
(define+provide coerce/path?
(make-contract
#:name 'coerce/path?
#:projection (make-blame-handler ->path 'can-be-path?)))
(define+provide coerce/boolean?
(make-contract
#:name 'coerce/boolean?
#:projection (make-blame-handler ->boolean 'can-be-boolean?)))