10 lines
259 B
Scheme
10 lines
259 B
Scheme
#lang scheme
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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 val (delay rhs))
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(define-syntax (id stx)
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(if (identifier? stx)
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#'(force val)
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(raise-syntax-error #f "bad syntax" stx))))) |