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18 lines
733 B
Racket
18 lines
733 B
Racket
#lang racket
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(require (for-syntax racket/base))
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(require "coercion/values.rkt")
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(provide when/block)
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;; improves the syntax for conditional blocks in templates
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;; ordinarily it would be @when[condition]{@list{stuff ...}}
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;; now it can be @when/block[condition]{stuff ...}
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;; has to be a macro otherwise body expressions will be evaluated regardless of condition
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;; this is bad: if condition is false, expression should exit
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(define-syntax (when/block stx)
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(syntax-case stx ()
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[(_ condition body ...)
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#'(if condition (string-append*
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(with-handlers ([exn:fail? (λ(exn) (error (format "when/block: ~a" (exn-message exn))))])
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(map ->string (list body ...))))
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"")])) |