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19 lines
613 B
Racket
19 lines
613 B
Racket
#lang racket/base
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(require (for-syntax racket/base) pollen/tag)
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(provide def/c (rename-out (top~ #%top)))
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;; Changes the default behavior of #%top.
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;; Unbound identifiers are allowed, and treated as the
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;; tag in a txexpr (with the rest of the expression treated as the body)
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;; To suppress this behavior, use def/c to wrap any name.
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;; If that name isn't already defined, you'll get the usual syntax error.
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(define-syntax-rule (top~ . ID)
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(make-default-tag-function 'ID))
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(define-syntax (def/c stx)
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(syntax-case stx ()
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[(_ X)
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(if (identifier-binding #'X )
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#'X
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#'(#%top . X))])) |