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.
53 lines
1.3 KiB
Racket
Executable File
53 lines
1.3 KiB
Racket
Executable File
#lang eopl
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;; builds environment interface, using data structures defined in
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;; data-structures.rkt.
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(require "data-structures.rkt")
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(provide init-env empty-env extend-env apply-env)
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;;;;;;;;;;;;;;;; initial environment ;;;;;;;;;;;;;;;;
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;; init-env : () -> Env
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;; usage: (init-env) = [i=1, v=5, x=10]
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;; (init-env) builds an environment in which i is bound to the
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;; expressed value 1, v is bound to the expressed value 5, and x is
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;; bound to the expressed value 10.
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;; Page: 69
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(define init-env
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(lambda ()
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(extend-env
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'i (num-val 1)
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(extend-env
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'v (num-val 5)
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(extend-env
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'x (num-val 10)
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(empty-env))))))
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;;;;;;;;;;;;;;;; environment constructors and observers ;;;;;;;;;;;;;;;;
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(define empty-env
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(lambda ()
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(empty-env-record)))
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(define empty-env?
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(lambda (x)
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(empty-env-record? x)))
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(define extend-env
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(lambda (sym val old-env)
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(extended-env-record sym val old-env)))
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(define apply-env
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(lambda (env search-sym)
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(if (empty-env? env)
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(eopl:error 'apply-env "No binding for ~s" search-sym)
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(let ((sym (extended-env-record->sym env))
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(val (extended-env-record->val env))
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(old-env (extended-env-record->old-env env)))
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(if (eqv? search-sym sym)
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val
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(apply-env old-env search-sym))))))
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