7491e172ea
The eopl language is now racket-based rather than mzscheme-based. This test-suite, which was originally distributed on the book's web-site has been re-written in the new language. Changes include dropping all drscheme-init.scm and top.scm files. Remaining files were renamed to use the .rkt extension and edited to use the #lang syntax (instead of modulue). Require and provide forms were changed to reflect racket's syntax instead of mzscheme's (eg, only-in vs. only). Several occurrences of one-armed ifs were changed to use when and unless. All tests have been run successfully.
79 lines
2.1 KiB
Racket
Executable File
79 lines
2.1 KiB
Racket
Executable File
#lang eopl
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(require "lang.rkt")
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(require "data-structures.rkt")
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(require "environments.rkt")
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(provide value-of-program value-of)
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;;;;;;;;;;;;;;;; the interpreter ;;;;;;;;;;;;;;;;
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;; value-of-program : Program -> Expval
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(define value-of-program
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(lambda (pgm)
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(cases program pgm
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(a-program (body)
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(value-of body (init-env))))))
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;; value-of : Exp * Env -> ExpVal
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(define value-of
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(lambda (exp env)
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(cases expression exp
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(const-exp (num) (num-val num))
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(var-exp (var) (apply-env env var))
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(diff-exp (exp1 exp2)
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(let ((val1
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(expval->num
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(value-of exp1 env)))
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(val2
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(expval->num
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(value-of exp2 env))))
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(num-val
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(- val1 val2))))
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(zero?-exp (exp1)
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(let ((val1 (expval->num (value-of exp1 env))))
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(if (zero? val1)
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(bool-val #t)
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(bool-val #f))))
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(if-exp (exp0 exp1 exp2)
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(if (expval->bool (value-of exp0 env))
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(value-of exp1 env)
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(value-of exp2 env)))
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(let-exp (var exp1 body)
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(let ((val (value-of exp1 env)))
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(value-of body
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(extend-env var val env))))
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(proc-exp (bvar ty body)
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(proc-val
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(procedure bvar body env)))
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(call-exp (rator rand)
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(let ((proc (expval->proc (value-of rator env)))
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(arg (value-of rand env)))
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(apply-procedure proc arg)))
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(letrec-exp (ty1 p-name b-var ty2 p-body letrec-body)
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(value-of letrec-body
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(extend-env-rec p-name b-var p-body env)))
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)))
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;; apply-procedure : Proc * ExpVal -> ExpVal
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(define apply-procedure
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(lambda (proc1 arg)
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(cases proc proc1
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(procedure (var body saved-env)
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(value-of body (extend-env var arg saved-env))))))
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