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23 lines
686 B
Racket
23 lines
686 B
Racket
#lang racket/base
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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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(require (for-syntax racket/base) pollen/tag)
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(provide (except-out (all-defined-out) top~)
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(rename-out (top~ #%top)))
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(define-syntax (top~ stx)
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(syntax-case stx ()
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[(_ . id) #'(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))])) |