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beautiful-racket/beautiful-racket-demo/scriptish-demo/expander.rkt

138 lines
3.7 KiB
Racket

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#lang br
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(require racket/stxparam)
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(provide (all-defined-out)
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#%app #%top #%datum #%top-interaction)
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(define-macro top #'#%module-begin)
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(define-macro-cases ternary
[(_ EXPR) #'EXPR]
[(_ COND TRUE-EXPR FALSE-EXPR) #'(if COND TRUE-EXPR FALSE-EXPR)])
(define-macro-cases logical-or
[(_ VAL) #'VAL]
[(_ L "||" R) #'(or L R)])
(define-macro-cases logical-and
[(_ VAL) #'VAL]
[(_ L "&&" R) #'(and L R)])
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(define-macro (my-app ID ARG ...)
#'(error 'boom))
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(define-macro-cases var
[(_ ID VAL) #'(define ID VAL)]
[(_ ID ... VAL) #'(begin (define ID VAL) ...)])
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(define (add/concat . xs)
(cond
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[(andmap number? xs) (let ([sum (apply + xs)])
(if (and (integer? sum) (inexact? sum))
(inexact->exact sum)
sum))]
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[(ormap string? xs) (string-join (map ~a xs) "")]))
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(define-macro-cases add-or-sub
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[(_ LEFT "+" RIGHT) #'(add/concat LEFT RIGHT)]
[(_ LEFT "-" RIGHT) #'(- LEFT RIGHT)]
[(_ OTHER) #'OTHER])
(define-macro-cases mult-or-div
[(_ LEFT "*" RIGHT) #'(* LEFT RIGHT)]
[(_ LEFT "/" RIGHT) #'(/ LEFT RIGHT)]
[(_ OTHER) #'OTHER])
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(define-macro (object (K V) ...)
#'(make-hash (list (cons K V) ...)))
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(define-syntax-parameter return
(λ (stx) (error 'not-parameterized)))
(define-macro (fun (ARG ...) STMT ...)
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(syntax/loc caller-stx
(λ (ARG ...)
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(let/cc return-cc
(syntax-parameterize ([return (make-rename-transformer #'return-cc)])
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(void) STMT ...)))))
(define-macro (defun ID (ARG ...) STMT ...)
#'(define ID (fun (ARG ...) STMT ...)))
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(define (resolve-deref base . keys)
(for/fold ([val base])
([key (in-list keys)])
(cond
[(and
(hash? val)
(cond
[(hash-ref val key #f)]
[(hash-ref val (symbol->string key) #f)]
[else #f]))]
[else (error 'deref-failure)])))
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(define-macro (deref (BASE KEY ...))
#'(resolve-deref BASE 'KEY ...))
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(define-macro app #'#%app)
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(define-macro-cases if-else
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[(_ COND TSTMT ... "else" FSTMT ...) #'(cond
[COND TSTMT ...]
[else FSTMT ...])]
[(_ COND STMT ...) #'(when COND STMT ...)])
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(define-macro-cases equal-or-not
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[(_ VAL) #'VAL]
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[(_ L "==" R) #'(equal? L R)]
[(_ L "!=" R) #'(not (equal? L R))])
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(define-macro-cases gt-or-lt
[(_ VAL) #'VAL]
[(_ L "<" R) #'(< L R)]
[(_ L "<=" R) #'(<= L R)]
[(_ L ">" R) #'(> L R)]
[(_ L ">=" R) #'(>= L R)])
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(define-macro (while COND STMT ...)
#'(let loop ()
(when COND
STMT ...
(loop))))
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(define (alert x) (displayln (format "ALERT! ~a" x)))
#;(require racket/gui)
#;(define (alert text)
(define dialog (instantiate dialog% ("Alert")))
(new message% [parent dialog] [label text])
(define panel (new horizontal-panel% [parent dialog]
[alignment '(center center)]))
(new button% [parent panel] [label "Ok"]
[callback (lambda (button event)
(send dialog show #f))])
(send dialog show #t))
(define-macro-cases increment
[(_ ID) #'ID]
[(_ "++" ID) #'(let ()
(set! ID (add1 ID))
ID)]
[(_ "--" ID) #'(let ()
(set! ID (sub1 ID))
ID)]
[(_ ID "++") #'(begin0
ID
(set! ID (add1 ID)))]
[(_ ID "--") #'(begin0
ID
(set! ID (sub1 ID)))])
(define-macro-cases reassignment
[(_ ID) #'ID]
[(_ ID "+=" EXPR) #'(let ()
(set! ID (+ ID EXPR))
ID)]
[(_ ID "-=" EXPR) #'(let ()
(set! ID (- ID EXPR))
ID)])