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beautiful-racket/beautiful-racket-demo/tacopocalypse-demo/main.rkt

34 lines
771 B
Racket

#lang br/quicklang
(require brag/support racket/sequence)
(module+ reader
(provide read-syntax))
(define lex
(lexer
["#$" null]
["%" 'taco]
[any-char (lex input-port)]))
(define (tokenize ip)
(define toklets
(for/list ([toklet (in-port lex ip)])
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toklet))
(for/list ([tok (in-slice 7 toklets)])
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tok))
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(define (parse src toks)
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(for/list ([tok (in-list toks)])
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(integer->char
(for/sum ([val (in-list tok)]
[power (in-naturals)]
#:when (eq? val 'taco))
(expt 2 power)))))
(define (read-syntax src ip)
(define toks (tokenize ip))
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(define parse-tree (parse src toks))
(strip-context
(with-syntax ([PT parse-tree])
#'(module untaco racket
(display (list->string 'PT))))))