11fd5a91ed
so when it shows up in an error message it doesn't take forever to figure out which 'val' that is original commit: 0ee8155527bf0118c1b035efdcc5a6a2fac4828a
13 lines
378 B
Racket
13 lines
378 B
Racket
#lang racket/base
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(require racket/promise
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(for-syntax racket/base))
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(provide define-on-demand)
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(define-syntax-rule (define-on-demand id rhs)
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(begin
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(define define-on-demand-bound-promise (delay rhs))
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(define-syntax (id stx)
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(if (identifier? stx)
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#'(force define-on-demand-bound-promise)
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(raise-syntax-error #f "bad syntax" stx)))))
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