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.
71 lines
1.5 KiB
Racket
Executable File
71 lines
1.5 KiB
Racket
Executable File
#lang eopl
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;; data structures for letrec-lang.
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(require "lang.rkt") ; for expression?
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(provide (all-defined-out)) ; too many things to list
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;;;;;;;;;;;;;;;; expressed values ;;;;;;;;;;;;;;;;
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;;; an expressed value is either a number, a boolean or a procval.
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(define-datatype expval expval?
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(num-val
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(value number?))
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(bool-val
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(boolean boolean?))
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(proc-val
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(proc proc?)))
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;;; extractors:
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;; expval->num : ExpVal -> Int
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(define expval->num
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(lambda (v)
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(cases expval v
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(num-val (num) num)
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(else (expval-extractor-error 'num v)))))
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;; expval->bool : ExpVal -> Bool
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(define expval->bool
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(lambda (v)
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(cases expval v
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(bool-val (bool) bool)
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(else (expval-extractor-error 'bool v)))))
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;; expval->proc : ExpVal -> Proc
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(define expval->proc
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(lambda (v)
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(cases expval v
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(proc-val (proc) proc)
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(else (expval-extractor-error 'proc v)))))
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(define expval-extractor-error
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(lambda (variant value)
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(eopl:error 'expval-extractors "Looking for a ~s, found ~s"
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variant value)))
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;;;;;;;;;;;;;;;; procedures ;;;;;;;;;;;;;;;;
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;; proc? : SchemeVal -> Bool
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;; procedure : Var * Exp * Env -> Proc
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(define-datatype proc proc?
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(procedure
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(bvar symbol?)
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(body expression?)
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(env environment?)))
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;; Page: 86
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(define-datatype environment environment?
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(empty-env)
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(extend-env
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(bvar symbol?)
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(bval expval?)
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(saved-env environment?))
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(extend-env-rec
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(id symbol?)
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(bvar symbol?)
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(body expression?)
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(saved-env environment?)))
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