mirror of
https://github.com/kanaka/mal.git
synced 2024-09-21 02:27:10 +03:00
63 lines
1.9 KiB
Scheme
63 lines
1.9 KiB
Scheme
(import (scheme base))
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(import (scheme write))
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(import (lib util))
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(import (lib reader))
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(import (lib printer))
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(import (lib types))
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(define (READ input)
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(read-str input))
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(define (eval-ast ast env)
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(let ((type (and (mal-object? ast) (mal-type ast)))
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(value (and (mal-object? ast) (mal-value ast))))
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(case type
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((symbol) (or (alist-ref value env)
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(error (str "'" value "' not found"))))
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((list) (mal-list (map (lambda (item) (EVAL item env)) value)))
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((vector) (mal-vector (vector-map (lambda (item) (EVAL item env)) value)))
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((map) (mal-map (alist-map (lambda (key value) (cons key (EVAL value env))) value)))
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(else ast))))
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(define (EVAL ast env)
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(let ((type (and (mal-object? ast) (mal-type ast))))
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(if (not (eq? type 'list))
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(eval-ast ast env)
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(let ((items (mal-value ast)))
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(if (null? items)
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ast
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(let* ((items (mal-value (eval-ast ast env)))
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(op (car items))
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(ops (cdr items)))
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(apply op ops)))))))
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(define (PRINT ast)
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(pr-str ast #t))
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(define repl-env
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`((+ . ,(lambda (a b) (mal-number (+ (mal-value a) (mal-value b)))))
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(- . ,(lambda (a b) (mal-number (- (mal-value a) (mal-value b)))))
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(* . ,(lambda (a b) (mal-number (* (mal-value a) (mal-value b)))))
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(/ . ,(lambda (a b) (mal-number (/ (mal-value a) (mal-value b)))))))
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(define (rep input)
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(PRINT (EVAL (READ input) repl-env)))
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(define (main)
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(let loop ()
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(let ((input (readline "user> ")))
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(when input
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(guard
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(ex ((error-object? ex)
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(when (not (memv 'empty-input (error-object-irritants ex)))
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(display "[error] ")
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(display (error-object-message ex))
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(newline))))
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(display (rep input))
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(newline))
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(loop))))
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(newline))
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(main)
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