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50 lines
1.3 KiB
Racket
Executable File
50 lines
1.3 KiB
Racket
Executable File
#!/usr/bin/env racket
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#lang racket
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(require "types.rkt" "readline.rkt" "reader.rkt" "printer.rkt")
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;; read
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(define (READ str)
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(read_str str))
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;; eval
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(define (eval-ast ast env)
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(cond
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[(symbol? ast)
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(or (hash-ref env ast
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(lambda () (raise (string-append "'"
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(symbol->string ast)
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"' not found")))))]
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[(_sequential? ast) (_map (lambda (x) (EVAL x env)) ast)]
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[(hash? ast) (make-hash
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(dict-map ast (lambda (k v) (cons k (EVAL v env)))))]
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[else ast]))
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(define (EVAL ast env)
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(if (or (not (list? ast)) (empty? ast))
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(eval-ast ast env)
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(let* ([el (eval-ast ast env)]
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[f (first el)]
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[args (rest el)])
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(apply f args))))
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;; print
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(define (PRINT exp)
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(pr_str exp true))
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;; repl
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(define repl-env (hash '+ + '- - '* * '/ /))
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(define (rep str)
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(PRINT (EVAL (READ str) repl-env)))
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(define (repl-loop)
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(let ([line (readline "user> ")])
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(when (not (eq? nil line))
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(with-handlers
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([string? (lambda (exc) (printf "Error: ~a~n" exc))]
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[blank-exn? (lambda (exc) null)])
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(printf "~a~n" (rep line)))
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(repl-loop))))
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(repl-loop)
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