59 lines
2.2 KiB
Racket
59 lines
2.2 KiB
Racket
#lang prospect
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;; A toy spreadsheet model.
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(require prospect/actor)
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(require racket/match)
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(require racket/set)
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(define-namespace-anchor ns)
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(struct cell (name value) #:transparent) ;; assertion
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(struct set-cell (name expr) #:transparent) ;; message
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(define (binding-symbol? s)
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(and (symbol? s)
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(let ((chars (string->list (symbol->string s))))
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(and (andmap char-alphabetic? chars)
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(pair? chars)
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(char-upper-case? (car chars))))))
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(define (extract-bindings expr)
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(let walk ((expr expr))
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(match expr
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[(? binding-symbol? b) (set b)]
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[(cons a d) (set-union (walk a) (walk d))]
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[_ (set)])))
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(define (non-void? v) (not (void? v)))
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(define (cell-expr->actor-expr name expr)
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(define bindings (set->list (extract-bindings expr)))
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`(actor (until (message (set-cell ',name _))
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#:collect [,@(for/list [(b bindings)] `(,b (void)))]
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(assert #:when (andmap non-void? (list ,@bindings)) (cell ',name ,expr))
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,@(for/list [(b bindings)]
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`(on (asserted (cell ',b $value))
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(values ,@(for/list [(b1 bindings)]
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(if (eq? b b1) 'value b1))))))))
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(actor (forever (on (message (set-cell $name $expr))
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(define actor-expr (cell-expr->actor-expr name expr))
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;; (local-require racket/pretty) (pretty-print actor-expr)
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(eval actor-expr (namespace-anchor->namespace ns)))))
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(actor (forever (on (asserted (cell $name $value))
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(printf ">>> ~a ~v\n" name value)
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(flush-output))))
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(actor (void (thread (lambda ()
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(let loop ()
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(define cell-name (read))
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(if (eof-object? cell-name)
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(send-ground-message 'quit)
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(let ((new-expr (read)))
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(send-ground-message (set-cell cell-name new-expr))
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(loop)))))))
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(until (message 'quit #:meta-level 1)
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(on (message (set-cell $name $expr) #:meta-level 1)
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(send! (set-cell name expr)))))
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