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pollen/pollen/top.rkt

19 lines
613 B
Racket

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