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

43 lines
1.1 KiB
Racket

#lang br/quicklang
(require brag/support "grammar.rkt")
(provide (all-defined-out) #%module-begin)
(module+ reader
(provide read-syntax))
(define-lex-abbrev reserved-toks
(:or "fun" "(" ")" "=" "+" "*" "/" "-" ","))
(define lex
(lexer
[(:or (from/to "//" "\n") (from/to "/*" "*/")) (token 'COMMENT #:skip? #t)]
[whitespace (lex input-port)]
[reserved-toks lexeme]
[alphabetic (token 'ID (string->symbol lexeme))]
[(:+ (char-set "0123456789")) (token 'INT (string->number lexeme))]))
(define-macro top #'begin)
(define-macro (func-def ID ARGIDS EXPR)
#'(define ID (λ ARGIDS EXPR)))
(define-macro-cases sum
[(_ LEFT "+" RIGHT) #'(+ LEFT RIGHT)]
[(_ LEFT "-" RIGHT) #'(- LEFT RIGHT)]
[(_ OTHER) #'OTHER])
(define-macro-cases product
[(_ LEFT OP-STR RIGHT)
(with-syntax ([OP (string->symbol (syntax->datum #'OP-STR))])
#'(OP LEFT RIGHT))]
[(_ OTHER) #'OTHER])
(define-macro func-app #'#%app)
(define (read-syntax src ip)
(define token-thunk (λ () (lex ip)))
(define parse-tree (parse token-thunk))
(strip-context
(with-syntax ([PT parse-tree])
#'(module mod-name precalc-demo
PT))))