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.
68 lines
2.0 KiB
Racket
Executable File
68 lines
2.0 KiB
Racket
Executable File
#lang eopl
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;; interpreter for the LET language. The \commentboxes are the
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;; latex code for inserting the rules into the code in the book.
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;; These are too complicated to put here, see the text, sorry.
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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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;; Page: 71
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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 (exp1)
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(value-of exp1 (init-env))))))
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;; value-of : Exp * Env -> ExpVal
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;; Page: 71
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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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;;\commentbox{ (value-of (const-exp \n{}) \r) = \n{}}
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(const-exp (num) (num-val num))
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;;\commentbox{ (value-of (var-exp \x{}) \r) = (apply-env \r \x{})}
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(var-exp (var) (apply-env env var))
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;;\commentbox{\diffspec}
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(diff-exp (exp1 exp2)
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(let ((val1 (value-of exp1 env))
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(val2 (value-of exp2 env)))
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(let ((num1 (expval->num val1))
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(num2 (expval->num val2)))
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(num-val
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(- num1 num2)))))
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;;\commentbox{\zerotestspec}
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(zero?-exp (exp1)
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(let ((val1 (value-of exp1 env)))
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(let ((num1 (expval->num val1)))
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(if (zero? num1)
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(bool-val #t)
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(bool-val #f)))))
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;;\commentbox{\ma{\theifspec}}
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(if-exp (exp1 exp2 exp3)
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(let ((val1 (value-of exp1 env)))
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(if (expval->bool val1)
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(value-of exp2 env)
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(value-of exp3 env))))
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;;\commentbox{\ma{\theletspecsplit}}
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(let-exp (var exp1 body)
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(let ((val1 (value-of exp1 env)))
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(value-of body
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(extend-env var val1 env))))
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)))
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