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beautiful-racket/beautiful-racket-ragg/br/ragg/examples/simple-line-drawing/semantics.rkt

49 lines
1.4 KiB
Racket

#lang racket/base
(require (for-syntax racket/base syntax/parse))
(provide #%module-begin
;; We reuse Racket's treatment of raw datums, specifically
;; for strings and numbers:
#%datum
;; And otherwise, we provide definitions of these three forms.
;; During compiliation, Racket uses these definitions to
;; rewrite into for loops, displays, and newlines.
drawing rows chunk)
;; Define a few compile-time functions to do the syntax rewriting:
(begin-for-syntax
(define (compile-drawing drawing-stx)
(syntax-parse drawing-stx
[({~literal drawing} row-stxs ...)
(syntax/loc drawing-stx
(begin row-stxs ...))]))
(define (compile-rows row-stx)
(syntax-parse row-stx
[({~literal rows}
({~literal repeat} repeat-number)
chunks ...
";")
(syntax/loc row-stx
(for ([i repeat-number])
chunks ...
(newline)))]))
(define (compile-chunk chunk-stx)
(syntax-parse chunk-stx
[({~literal chunk} chunk-size chunk-string)
(syntax/loc chunk-stx
(for ([k chunk-size])
(display chunk-string)))])))
;; Wire up the use of "drawing", "rows", and "chunk" to these
;; transformers:
(define-syntax drawing compile-drawing)
(define-syntax rows compile-rows)
(define-syntax chunk compile-chunk)