Aminet 1/Aminet - June 1993 [Walnut Creek].iso/usenet/sources/volume90/aplictns/xscheme2/part07

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Path: xanth!cs.odu.edu!Amiga-Request
From: [e-mail] (Amiga Sources/Binaries Moderator)
Newsgroups: comp.sources.amiga
Subject: v90i145: XScheme 0.20 - an object-oriented scheme, Part07/07
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Date: 14 Apr 90 21:15:17 GMT
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Submitted-by: [e-mail] (Rusty Haddock)
Posting-number: Volume 90, Issue 145
Archive-name: applications/xscheme-0.20/part07

#!/bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of archive 7 (of 7)."
# Contents:  xscheme.doc
# Wrapped by tadguy@xanth on Sat Apr 14 17:07:32 1990
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'xscheme.doc' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'xscheme.doc'\"
else
echo shar: Extracting \"'xscheme.doc'\" \(52550 characters\)
sed "s/^X//" >'xscheme.doc' <<'END_OF_FILE'
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X                       XSCHEME: An Object-oriented Scheme
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X                                  Version 0.17
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X                                 March 2, 1989
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X                                       by
X                               David Michael Betz
X                                  P.O. Box 144
X                             Peterborough, NH 03458
X
X                             [phone] (home)
X
X                   Copyright (c) 1989, by David Michael Betz
X                              All Rights Reserved
X           Permission is granted for unrestricted non-commercial use
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X        XSCHEME                TABLE OF CONTENTS                  Page 2
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X        TABLE OF CONTENTS
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X            TABLE OF CONTENTS..................................2
X            INTRODUCTION.......................................3
X            A NOTE FROM THE AUTHOR.............................4
X            EXPRESSIONS........................................5
X            BINDING FORMS.....................................10
X            SEQUENCING........................................11
X            DELAYED EVALUATION................................12
X            ITERATION.........................................13
X            DEFINITIONS.......................................14
X            LIST FUNCTIONS....................................15
X            DESTRUCTIVE LIST FUNCTIONS........................17
X            SYMBOL FUNCTIONS..................................18
X            VECTOR FUNCTIONS..................................19
X            ARRAY FUNCTIONS...................................20
X            CONVERSION FUNCTIONS..............................21
X            TYPE PREDICATES...................................22
X            EQUALITY PREDICATES...............................25
X            ARITHMETIC FUNCTIONS..............................26
X            NUMERIC COMPARISON FUNCTIONS......................29
X            BITWISE LOGICAL FUNCTIONS.........................30
X            STRING FUNCTIONS..................................31
X            STRING COMPARISON FUNCTIONS.......................32
X            CHARACTER COMPARISON FUNCTIONS....................33
X            INPUT/OUTPUT FUNCTIONS............................34
X            OUTPUT CONTROL FUNCTIONS..........................36
X            FILE I/O FUNCTIONS................................37
X            CONTROL FEATURES..................................39
X            ENVIRONMENT FUNCTIONS.............................40
X            UTILITY FUNCTIONS.................................41
X            SYSTEM FUNCTIONS..................................42
X            OBJECT REPRESENTATIONS............................43
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X        XSCHEME                   INTRODUCTION                    Page 3
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X        XScheme is an implementation of the Scheme programming language
X        with extensions to support object-oriented programming.
X
X        There are currently implementations of XScheme running on the
X        IBM-PC and clones under MS-DOS, on the Macintosh, the Atari-ST
X        and the Amiga.  It is completely written in the programming
X        language 'C' and is easily extended with user written built-in
X        functions and classes.  It is available in source form to non-
X        commercial users.
X
X        This document is a brief description of XScheme.  XScheme
X        follows the "Revised^3 Report on the Algorithmic Language
X        Scheme".  It assumes some knowledge of Scheme or LISP and some
X        understanding of the concepts of object-oriented programming.
X
X        I recommend the book "Structure and Interpretation of Computer
X        Programs" by Harold Abelson and Gerald Jay Sussman and published
X        by The MIT Press and the McGraw-Hill Book Company for learning
X        Scheme (and programming in general).  You might also find "The
X        Scheme Programming Language" by R. Kent Dybvig and "The Little
X        Lisper" by Daniel P. Friedman and Matthias Felleisen to be
X        helpful.
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X        XSCHEME              A NOTE FROM THE AUTHOR               Page 4
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X        A NOTE FROM THE AUTHOR
X
X        If you have any problems with XScheme, feel free to contact me
X        for help or advice.  Please remember that since XScheme is
X        available in source form in a high level language, many users
X        have been making versions available on a variety of machines.
X        If you call to report a problem with a specific version, I may
X        not be able to help you if that version runs on a machine to
X        which I don't have access.  Please have the version number of
X        the version that you are running readily accessible before
X        calling me.
X
X        If you find a bug in XScheme, first try to fix the bug yourself
X        using the source code provided.  If you are successful in fixing
X        the bug, send the bug report along with the fix to me.  If you
X        don't have access to a C compiler or are unable to fix a bug,
X        please send the bug report to me and I'll try to fix it.
X
X        Any suggestions for improvements will be welcomed.  Feel free to
X        extend the language in whatever way suits your needs.  However,
X        PLEASE DO NOT RELEASE ENHANCED VERSIONS WITHOUT CHECKING WITH ME
X        FIRST!!  I would like to be the clearing house for new features
X        added to XScheme.  If you want to add features for your own
X        personal use, go ahead.  But, if you want to distribute your
X        enhanced version, contact me first.
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X        XSCHEME                   EXPRESSIONS                     Page 5
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X        EXPRESSIONS
X
X        <variable>
X
X            An expression consisting of a variable is a variable
X            reference.  The value of the variable reference is the value
X            stored in the location to which the variable is bound.  It
X            is an error to reference an unbound variable.
X
X        (QUOTE <datum>)
X        '<datum>
X
X            (quote <datum>) evaluates to <datum>.  <Datum> may be any
X            external representation of a Scheme object.  This notation
X            is used to include literal constants in Scheme code.  (quote
X            <datum>) may be abbreviated as '<datum>.  The two notations
X            are equivalent in all respects.
X
X        <constant>
X
X            Numeric constants, string constants, character constants,
X            and boolean constants evaluate "to themselves"; they need
X            not be quoted.
X
X        (<operator> <operand>...)
X
X            A procedure call is written by simply enclosing in
X            parentheses expressions for the procedure to be called and
X            the arguments to be passed to it.  The operator and operand
X            expressions are evaluated and the resulting procedure is
X            passed the resulting arguments.
X
X        (<object> <selector> <operand>...)
X
X            A message sending form is written by enclosing in
X            parentheses expressions for the receiving object, the
X            message selector, and the arguments to be passed to the
X            method.  The receiver, selector, and argument expressions
X            are evaluated, the message selector is used to select an
X            appropriate method to handle the message, and the resulting
X            method is passed the resulting arguments.
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X        XSCHEME                   EXPRESSIONS                     Page 6
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X        (LAMBDA <formals> <body>)
X
X            <Formals> should be a formal argument list as described
X            below, and <body>  should be a sequence of one or more
X            expressions.  A lambda expression evaluates to a procedure.
X            The environment in effect when the lambda expression is
X            evaluated is remembered as part of the procedure.  When the
X            procedure is later called with some actual arguments, the
X            environment in which the lambda expression was evaluated
X            will be extended by binding the variables in the formal
X            argument list to fresh locations, the corresponding actual
X            argument values will be stored in those locations, and the
X            expressions in the body of the lambda expression will be
X            evaluated sequentially in the extended environment.  The
X            result of the last expression in the body will be returned
X            as the result of the procedure call.
X
X            <Formals> should have the following form:
X
X                (<var>... [#!OPTIONAL <ovar>...] [. <rvar>])
X              or
X                (<var>... [#!OPTIONAL <ovar>...] [#!REST <rvar>])
X
X              where:
X
X                <var>    is a required argument
X                <ovar>   is an optional argument
X                <rvar>   is a "rest" argument
X
X            There are three parts to a <formals> list.  The first lists
X            the required arguments of the procedure.  All calls to the
X            procedure must supply values for each of the required
X            arguments.  The second part lists the optional arguments of
X            the procedure.  An optional argument may be supplied in a
X            call or omitted.  If it is omitted, a special value is given
X            to the argument that satisfies the default-object?
X            predicate.  This provides a way to test to see if an
X            optional argument was provided in a call or omitted.  The
X            last part of the <formals> list gives the "rest" argument.
X            This argument will be bound to the rest of the list of
X            arguments supplied to a call after the required and optional
X            arguments have been removed.
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X        XSCHEME                   EXPRESSIONS                     Page 7
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X        (IF <test> <consequent> [<alternate>])
X
X            An if expression is evaluated as follows:  first, <test> is
X            evaluated.  If it yields a true value, then <consequent> is
X            evaluated and its value is returned.  Otherwise, <alternate>
X            is evaluated and its value is returned.  If <test> yields a
X            false value and no <alternate> is specified, then the result
X            of the expression is unspecified.
X
X        (ACCESS <variable> <env>)
X
X            <Env> is evaluated producing an environment.  The result is
X            the value of <variable> in this environment.
X
X        (SET! <variable> <expression>)
X
X            <Expression> is evaluated, and the resulting value is stored
X            in the location to which <variable> is bound.  <Variable>
X            must be bound in some region or at the top level. The result
X            of the set! expression is unspecified.
X
X        (SET! (ACCESS <variable> <env>) <value>)
X
X            <Env> is evaluated producing an environment.  <Value> is
X            evaluated and the resulting value is stored as the value of
X            <variable> in this environment.  The result of the set!
X            expression is unspecified.
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X        XSCHEME                   EXPRESSIONS                     Page 8
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X        (COND <clause>...)
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X            Each clause should be of the form
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X                (<test> <expression>...)
X
X            where <test> is any expression.  The last <clause> may be an
X            "else clause," which has the form
X
X                (ELSE <expression>...)
X
X            A cond expression is evaluated by evaluating the <test>
X            expressions of successive <clause>s in order until one of
X            them evaluates to a true value.  When a <test> evaluates to
X            a true value, then the remaining <expression>s in its
X            <clause> are evaluated in order, and the result of the last
X            <expression> in the <clause> is returned as the result of
X            the entire cond expression.  If the selected <clause>
X            contains only the <test> and no <expression>s, then the
X            value of the <test> is returned as the result.  If all
X            <test>s evaluate to false values, and there is no else
X            clause, then the result of the conditional expression is
X            unspecified; if there is an else clause, then its
X            <expression>s are evaluated, and the value of the last one
X            is returned.
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X        XSCHEME                   EXPRESSIONS                     Page 9
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X        (AND <test>...)
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X            The <test> expressions are evaluated from left to right, and
X            the value of the first expression that evaluates to a false
X            value is returned.  Any remaining expressions are not
X            evaluated.  If all the expressions evaluate to true values,
X            the value of the last expression is returned.  If there are
X            no expressions then #t is returned.
X
X        (OR <test>...)
X
X            The <test> expressions are evaluated from left to right, and
X            the value of the first expression that evaluates to a true
X            value is returned.  Any remaining expressions are not
X            evaluated.  If all expressions evaluate to false values, the
X            value of the last expression is returned.  If there are no
X            expressions then #f is returned.
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X        XSCHEME                  BINDING FORMS                   Page 10
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X        BINDING FORMS
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X        (LET [<name>] <bindings> <body>)
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X            <Bindings> should have the form
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X                ((<variable> <init>)...)
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X            where each <init> is an expression, and <body> should be a
X            sequence of one or more expressions.  The <init>s are
X            evaluated in the current envirnoment, the <variable>s are
X            bound to fresh locations holding the results, the <body> is
X            evaluated in the extended environment, and the value of the
X            last expression of <body> is returned.  Each binding of a
X            <variable> has <body> as its region.
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X            If a name is supplied, a procedure that takes the bound
X            variables as its arguments and has the body of the LET as
X            its body is bound to that name.
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X        (LET* <bindings> <body>)
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X            Same as LET except that the bindings are done sequentially
X            from left to right and the bindings to the left are visible
X            while evaluating the initialization expressions for each
X            variable.
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X        (LETREC <bindings> <body>)
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X            <Bindings> should have the form
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X                ((<variable> <init>)...)
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X            and <body> should be a sequence of one or more expressions.
X            The <variable>s are bound to fresh locations holding
X            undefined values; the <init>s are evaluated in the resulting
X            environment; each <variable>  is assigned to the result of
X            the corresponding <init>; the <body> is evaluated in the
X            resulting environment; and the value of the last expression
X            in <body> is returned.  Each binding of a <variable> has the
X            entire letrec expression as its region, making it possible
X            to define mutually recursive procedures.  One restriction of
X            letrec is very important:  it must be possible to evaluate
X            each <init> without referring to the value of any
X            <variable>.  If this restriction is violated, then the
X            effect is undefined, and an error may be signalled during
X            evaluation of the <init>s.  The restriction is necessary
X            because Scheme passes arguments by value rather than by
X            name.  In the most common uses of letrec, all the <init>s
X            are lambda expressions and the restriction is satisfied
X            automatically.
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X        XSCHEME                    SEQUENCING                    Page 11
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X            SEQUENCING
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X            (BEGIN <expression>...)
X            (SEQUENCE <expression>...)
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X                The <expression>s are evaluated sequentially from left
X                to right, and the value of the last <expression> is
X                returned.  This expression type is used to sequence side
X                effects such as input and output.
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X        XSCHEME                DELAYED EVALUATION                Page 12
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X            DELAYED EVALUATION
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X            (CONS-STREAM expr1 expr2)
X
X                Create a cons stream whose head is expr1 (which is
X                evaluated immediately) and whose tail is expr2 (whose
X                evaluation is delayed until TAIL is called).  To use
X                CONS-STREAM, enter the following access procedures:
X
X                    (define head car)
X                    (define (tail stream) (force (cdr stream)))
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X            (DELAY <expression>)
X
X                Evaluating this expression creates a "promise" to
X                evaluate <expression>  at a later time.
X
X            (FORCE promise)
X
X                Applying FORCE to a promise generated by DELAY requests
X                that the promise produce the value of the expression
X                passed to DELAY.  The first time a promise is FORCEed,
X                the DELAY expression is evaluated and the value stored.
X                On subsequent calls to FORCE with the same promise, the
X                saved value is returned.
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X        XSCHEME                    ITERATION                     Page 13
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X            ITERATION
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X            (WHILE <test> <expression>...)
X
X                While is an iteration construct.  Each iteration begins
X                by evaluating <test>; if the result is false, then the
X                loop terminates and the value of <test> is returned as
X                the value of the while expression.  If <test>  evaluates
X                to a true value, then the <expression>s are evaluated in
X                order for effect and the next iteration begins.
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X        XSCHEME                   DEFINITIONS                    Page 14
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X            DEFINITIONS
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X            (DEFINE <variable> <expression>)
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X                Define a variable and give it an initial value.
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X            (DEFINE (<variable> <formals>) <body>)
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X                Define a procedure.
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X        XSCHEME                  LIST FUNCTIONS                  Page 15
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X            LIST FUNCTIONS
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X            (CONS expr1 expr2)
X
X                Create a new pair whose car is expr1 and whose cdr is
X                expr2.
X
X            (CAR pair)
X
X                Extract the car of a pair.
X
X            (CDR pair)
X
X                Extract the cdr of a pair.
X
X            (CxxR pair)
X            (CxxxR pair)
X            (CxxxxR pair)
X
X                These functions are short for combinations of CAR and
X                CDR.  Each 'x' is stands for either 'A' or 'D'.  An 'A'
X                stands for the CAR function and a 'D' stands for the CDR
X                function.  For instance, (CADR x) is the same as (CAR
X                (CDR x)).
X
X            (LIST expr...)
X
X                Create a list whose elements are the arguments to the
X                function.  This function can take an arbitrary number of
X                arguments.  Passing no arguments results in the empty
X                list.
X
X            (APPEND list...)
X
X                Append lists to form a single list.  This function takes
X                an arbitrary number of arguments.  Passing no arguments
X                results in the empty list.
X
X            (REVERSE list)
X
X                Create a list whose elements are the same as the
X                argument except in reverse order.
X
X            (LAST-PAIR list)
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X                Return the last pair in a list.
X
X            (LENGTH list)
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X                Compute the length of a list.
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X        XSCHEME                  LIST FUNCTIONS                  Page 16
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X            (MEMBER expr list)
X            (MEMV expr list)
X            (MEMQ expr list)
X
X                Find an element in a list.  Each of these functions
X                searches the list looking for an element that matches
X                expr.  If a matching element is found, the remainder of
X                the list starting with that element is returned.  If no
X                matching element is found, the empty list is returned.
X                The functions differ in the test used to determine if an
X                element matches expr.  The MEMBER function uses EQUAL?,
X                the MEMV function uses EQV?  and the MEMQ function uses
X                EQ?.
X
X            (ASSOC expr alist)
X            (ASSV expr alist)
X            (ASSQ expr alist)
X
X                Find an entry in an association list.  An association
X                list is a list of pairs.  The car of each pair is the
X                key and the cdr is the value.  These functions search an
X                association list for a pair whose key matches expr.  If
X                a matching pair is found, it is returned.  Otherwise,
X                the empty list is returned.  The functions differ in the
X                test used to determine if a key matches expr.  The ASSOC
X                function uses EQUAL?, the ASSV function uses EQV?  and
X                the ASSQ function uses EQ?.
X
X            (LIST-REF list n)
X
X                Return the nth element of a list (zero based).
X
X            (LIST-TAIL list n)
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X                Return the sublist obtained by removing the first n
X                elements of list.
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X        XSCHEME            DESTRUCTIVE LIST FUNCTIONS            Page 17
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X            DESTRUCTIVE LIST FUNCTIONS
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X            (SET-CAR! pair expr)
X
X                Set the car of a pair to expr.  The value returned by
X                this procedure is unspecified.
X
X            (SET-CDR! pair expr)
X
X                Set the cdr of a pair to expr.  The value returned by
X                this procedure is unspecified.
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X        XSCHEME                 SYMBOL FUNCTIONS                 Page 18
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X            SYMBOL FUNCTIONS
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X            (BOUND? sym)
X
X                Returns #t if a global value is bound to the symbol and
X                #f otherwise.
X
X            (SYMBOL-VALUE sym)
X
X                Get the global value of a symbol.
X
X            (SET-SYMBOL-VALUE! sym expr)
X
X                Set the global value of a symbol.  The value returned by
X                this procedure is unspecified.
X
X            (SYMBOL-PLIST sym)
X
X                Get the property list associated with a symbol.
X
X            (SET-SYMBOL-PLIST! sym plist)
X
X                Set the property list associate with a symbol.  The
X                value returned by this procedure is unspecified.
X
X            (GENSYM [sym|str|num])
X
X                Generate a new, uninterned symbol.  The print name of
X                the symbol will consist of a prefix with a number
X                appended.  The initial prefix is "G" and the initial
X                number is 1.  If a symbol is specified as an argument,
X                the prefix is set to the print name of that symbol.  If
X                a string is specified, the prefix is set to that string.
X                If a number is specified, the numeric suffix is set to
X                that number.  After the symbol is generated, the number
X                is incremented so subsequent calls to GENSYM will
X                generate numbers in sequence.
X
X            (GET sym prop)
X
X                Get the value of a property of a symbol.  The prop
X                argument is a symbol that is the property name.  If a
X                property with that name exists on the symbols property
X                list, the value of the property is returned.  Otherwise,
X                the empty list is returned.
X
X            (PUT sym prop expr)
X
X                Set the value of a property of a symbol.  The prop
X                argument is a symbol that is the property name.  The
X                property/value combination is added to the property list
X                of the symbol.
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 VECTOR FUNCTIONS                 Page 19
X
X
X            VECTOR FUNCTIONS
X
X            (VECTOR expr...)
X
X                Create a vector whose elements are the arguments to the
X                function.  This function can take an arbitrary number of
X                arguments.  Passing no arguments results in a zero
X                length vector.
X
X            (MAKE-VECTOR len)
X
X                Make a vector of the specified length.
X
X            (VECTOR-LENGTH vect)
X
X                Get the length of a vector.
X
X            (VECTOR-REF vect n)
X
X                Return the nth element of a vector (zero based).
X
X            (VECTOR-SET! vect n expr)
X
X                Set the nth element of a vector (zero based).
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 ARRAY FUNCTIONS                  Page 20
X
X
X            ARRAY FUNCTIONS
X
X            (MAKE-ARRAY d1 d2...)
X
X                Make an array (vector of vectors) with the specified
X                dimensions.  At least one dimension must be specified.
X
X            (ARRAY-REF array s1 s2...)
X
X                Get an array element.  The sn arguments are integer
X                subscripts (zero based).
X
X            (ARRAY-SET! array s1 s2... expr)
X
X                Set an array element.  The sn arguments are integer
X                subscripts (zero based).
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME               CONVERSION FUNCTIONS               Page 21
X
X
X            CONVERSION FUNCTIONS
X
X            (SYMBOL->STRING sym)
X
X                Convert a symbol to a string.  Returns the print name of
X                the symbol as a string.
X
X            (STRING->SYMBOL str)
X
X                Convert a string to a symbol.  Returns a symbol with the
X                string as its print name.  This can either be a new
X                symbol or an existing one with the same print name.
X
X            (VECTOR->LIST vect)
X
X                Convert a vector to a list.  Returns a list of the
X                elements of the vector.
X
X            (LIST->VECTOR list)
X
X                Convert a list to a vector.  Returns a vector of the
X                elements of the list.
X
X            (STRING->LIST str)
X
X                Convert a string to a list.  Returns a list of the
X                characters in the string.
X
X            (LIST->STRING list)
X
X                Convert a list of character to a string.  Returns a
X                string whose characters are the elements of the list.
X
X            (CHAR->INTEGER char)
X
X                Convert a character to an integer.  Returns the ASCII
X                code of the character as an integer.
X
X            (INTEGER->CHAR n)
X
X                Convert an integer ASCII code to a character.  Returns
X                the character whose ASCII code is the integer.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 TYPE PREDICATES                  Page 22
X
X
X            TYPE PREDICATE FUNCTIONS
X
X            (NOT expr)
X
X                Returns #t if the expression is #f and #t otherwise.
X
X            (NULL? expr)
X
X                Returns #t if the expression is the empty list and #f
X                otherwise.
X
X            (ATOM? expr)
X
X                Returns #f if the expression is a pair and #t otherwise.
X
X            (LIST? expr)
X
X                Returns #t if the expression is either a pair or the
X                empty list and #f otherwise.
X
X            (NUMBER? expr)
X
X                Returns #t if the expression is a number and #f
X                otherwise.
X
X            (BOOLEAN? expr)
X
X                Returns #t if the expression is either #t or #f and #f
X                otherwise.
X
X            (PAIR? expr)
X
X                Returns #t if the expression is a pair and #f otherwise.
X
X            (SYMBOL? expr)
X
X                Returns #t if the expression is a symbol and #f
X                otherwise.
X
X            (COMPLEX? expr)
X
X                Returns #t if the expression is a complex number and #f
X                otherwise.
X                Note:  Complex numbers are not yet supported by XScheme.
X
X            (REAL? expr)
X
X                Returns #t if the expression is a real number and #f
X                otherwise.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 TYPE PREDICATES                  Page 23
X
X
X            (RATIONAL? expr)
X
X                Returns #t if the expression is a rational number and #f
X                otherwise.
X                Note:  Rational numbers are not yet supported by
X                XScheme.
X
X            (INTEGER? expr)
X
X                Returns #t if the expression is an integer and #f
X                otherwise.
X
X            (CHAR? expr)
X
X                Returns #t if the expression is a character and #f
X                otherwise.
X
X            (STRING? expr)
X
X                Returns # if the expression is a string and #f
X                otherwise.
X
X            (VECTOR? expr)
X
X                Returns #t if the expression is a vector and #f
X                otherwise.
X
X            (PROCEDURE? expr)
X
X                Returns #t if the expression is a procedure (closure)
X                and #f otherwise.
X
X            (PORT? expr)
X
X                Returns #t if the expression is a port and #f otherwise.
X
X            (INPUT-PORT? expr)
X
X                Returns #t if the expression is an input port and #f
X                otherwise.
X
X            (OUTPUT-PORT? expr)
X
X                Returns #t if the expression is an output port and #f
X                otherwise.
X
X            (OBJECT? expr)
X
X                Returns #t if the expression is an object and #f
X                otherwise.
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 TYPE PREDICATES                  Page 24
X
X
X            (EOF-OBJECT? expr)
X
X                Returns #t if the expression is the object returned by
X                READ upon detecting an end of file condition and #f
X                otherwise.
X
X            (DEFAULT-OBJECT? expr)
X
X                Returns #t if the expression is the object passed as the
X                default value of an optional parameter to a procedure
X                when that parameter is omitted from a call and #f
X                otherwise.
X
X            (ENVIRONMENT? x)
X
X                Returns #t if the expression is an environment and #f
X                otherwise.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME               EQUALITY PREDICATES                Page 25
X
X
X            EQUALITY PREDICATES
X
X            (EQUAL? expr1 expr2)
X
X                Recursively compares two objects to determine if their
X                components are the same and returns #t if they are the
X                same and #f otherwise.
X
X            (EQV? expr1 expr2)
X
X                Compares two objects to determine if they are the same
X                object.  Returns #t if they are the same and #f
X                otherwise.  This function does not compare the elements
X                of lists, vectors or strings but will compare all types
X                of numbers.
X
X            (EQ? expr1 expr2)
X
X                Compares two objects to determine if they are the same
X                object.  Returns #t if they are the same and #f
X                otherwise.  This function performs a low level address
X                compare on two objects and may return #f for objects
X                that appear on the surface to be the same.  This is
X                because the objects are not stored uniquely in memory.
X                For instance, numbers may appear to be equal, but EQ?
X                will return #f when comparing them if they are stored at
X                different addresses.  The advantage of this function is
X                that it is faster than the others.  Symbols are
X                guaranteed to compare correctly, so EQ? can safely be
X                used to compare them.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME               ARITHMETIC FUNCTIONS               Page 26
X
X
X            ARITHMETIC FUNCTIONS
X
X            (ZERO? n)
X
X                Returns #t if the number is zero and #f otherwise.
X
X            (POSITIVE? n)
X
X                Returns #t if the number is positive and #f otherwise.
X
X            (NEGATIVE? n)
X
X                Returns #t if the number is negative and #f otherwise.
X
X            (ODD? n)
X
X                Returns #t if the integer is odd and #f otherwise.
X
X            (EVEN? n)
X
X                Returns #t if the integer is even and #f otherwise.
X
X            (EXACT? n)
X
X                Returns #t if the number is exact and #f otherwise.
X                Note:  This function always returns #f in XScheme since
X                exact numbers are not yet supported.
X
X            (INEXACT? n)
X
X                Returns #t if the number is inexact and #f otherwise.
X                Note:  This function always returns #t in XScheme since
X                exact numbers are not yet supported.
X
X            (TRUNCATE n)
X
X                Truncates a number to an integer and returns the
X                resulting value.
X
X            (FLOOR n)
X
X                Returns the largest integer not larger than n.
X
X            (CEILING n)
X
X                Returns the smallest integer not smaller than n.
X
X            (ROUND n)
X
X                Returns the closest integer to n, rounding to even when
X                n is halfway between two integers.
X
X            (1+ n)
X
X
X
X
X
X
X
X
X
X
X        XSCHEME               ARITHMETIC FUNCTIONS               Page 27
X
X
X                Returns the result of adding one to the number.
X
X            (-1+ n)
X
X                Returns the result of subtracting one from the number.
X
X            (ABS n)
X
X                Returns the absolute value of the number.
X
X            (GCD n1 n2)
X
X                Returns the greatest common divisor of the two numbers.
X
X            (RANDOM n)
X
X                Returns a random number between zero and n-1 (n must be
X                an integer).
X
X            (+ n1 n2...)
X
X                Returns the sum of the numbers.
X
X            (- n)
X
X                Negates the number and returns the resulting value.
X
X            (- n1 n2...)
X
X                Subtracts each remaining number from n1 and returns the
X                resulting value.
X
X            (* n1 n2...)
X
X                Multiples the numbers and returns the resulting value.
X
X            (/ n)
X
X                Returns 1/n.
X
X            (/ n1 n2...)
X
X                Divides n1 by each of the remaining numbers and returns
X                the resulting value.
X
X            (QUOTIENT n1 n2...)
X
X                Divides the integer n1 by each of the remaining numbers
X                and returns the resulting integer quotient.  This
X                function does integer division.
X
X            (REMAINDER n1 n2)
X
X                Divides the integer n1 by the integer n2 and returns the
X
X
X
X
X
X
X
X
X
X        XSCHEME               ARITHMETIC FUNCTIONS               Page 28
X
X
X                remainder.
X
X            (MIN n1 n2...)
X
X                Returns the number with the minimum value.
X
X            (MAX n1 n2...)
X
X                Returns the number with the maximum value.
X
X            (SIN n)
X
X                Returns the sine of the number.
X
X            (COS n)
X
X                Returns the cosine of the number.
X
X            (TAN n)
X
X                Returns the tangent of the number.
X
X            (ASIN n)
X
X                Returns the arc-sine of the number.
X
X            (ACOS n)
X
X                Returns the arc-cosine of the number.
X
X            (ATAN x)
X
X                Returns the arc-tangent of x.
X
X            (ATAN y x)
X
X                Returns the arc-tangent of y/x.
X
X            (EXP n)
X
X                Returns e raised to the n.
X
X            (SQRT n)
X
X                Returns the square root of n.
X
X            (EXPT n1 n2)
X
X                Returns n1 raised to the n2 power.
X
X            (LOG n)
X
X                Returns the natural logarithm of n.
X
X
X
X
X
X
X
X
X
X
X        XSCHEME           NUMERIC COMPARISON FUNCTIONS           Page 29
X
X
X            NUMERIC COMPARISON FUNCTIONS
X
X            (< n1 n2...)
X            (= n1 n2...)
X            (> n1 n2...)
X            <<= n1 n2...)
X            (>= n1 n2...)
X
X                These functions compare numbers and return #t if the
X                numbers match the predicate and #f otherwise.  For
X                instance, (< x y z) will return #t if x is less than y
X                and y is less than z.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME            BITWISE LOGICAL FUNCTIONS             Page 30
X
X
X            BITWISE LOGICAL FUNCTIONS
X
X            (LOGAND n1 n2...)
X
X                Returns the bitwise AND of the integer arguments.
X
X            (LOGIOR n1 n2...)
X
X                Returns the bitwise inclusive OR of the integer
X                arguments.
X
X            (LOGXOR n1 n2...)
X
X                Returns the bitwise exclusive OR of the integer
X                arguments.
X
X            (LOGNOT n)
X
X                Returns the bitwise complement of n.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 STRING FUNCTIONS                 Page 31
X
X
X            STRING FUNCTIONS
X
X            (STRING-LENGTH str)
X
X                Returns the length of the string.
X
X            (STRING-NULL? str)
X
X                Returns #t if the string has a length of zero and #f
X                otherwise.
X
X            (STRING-APPEND str1...)
X
X                Returns the result of appending the string arguments.
X                If no arguments are supplied, it returns the null
X                string.
X
X            (STRING-REF str n)
X
X                Returns the nth character in a string.
X
X            (SUBSTRING str start end)
X
X                Returns the substring of str starting at start and
X                ending at end (integers).  The range is inclusive of
X                start and exclusive of end.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME           STRING COMPARISON FUNCTIONS            Page 32
X
X
X            STRING COMPARISON FUNCTIONS
X
X            (STRING<? str1 str2)
X            (STRING=? str1 str2)
X            (STRING>? str1 str2)
X            (STRING<=? str1 str2)
X            (STRING>=? str1 str2)
X
X                These functions compare strings and return #t if the
X                strings match the predicate and #f otherwise.  For
X                instance, (STRING< x y) will return #t if x is less than
X                y.  Case is significant.  #A does not match #a.
X
X            (STRING-CI<? str1 str2)
X            (STRING-CI=? str1 str2)
X            (STRING-CI>? str1 str2)
X            (STRING-CI<=? str1 str2)
X            (STRING-CI>=? str1 str2)
X
X                These functions compare strings and return #t if the
X                strings match the predicate and #f otherwise.  For
X                instance, (STRING-CI< x y) will return #t if x is less
X                than y.  Case is not significant.  #A matches #a.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME          CHARACTER COMPARISON FUNCTIONS          Page 33
X
X
X            CHARACTER COMPARISON FUNCTIONS
X
X            (CHAR<? ch1 ch2)
X            (CHAR=? ch1 ch2)
X            (CHAR>? ch1 ch2)
X            (CHAR<=? ch1 ch2)
X            (CHAR>=? ch1 ch2)
X
X                These functions compare characters and return #t if the
X                characters match the predicate and #f otherwise.  For
X                instance, (CHAR< x y) will return #t if x is less than
X                y.  Case is significant.  #A does not match #a.
X
X            (CHAR-CI<? ch1 ch2)
X            (CHAR-CI=? ch1 ch2)
X            (CHAR-CI>? ch1 ch2)
X            (CHAR-CI<=? ch1 ch2)
X            (CHAR-CI>=? ch1 ch2)
X
X                These functions compare characters and return #t if the
X                characters match the predicate and #f otherwise.  For
X                instance, (CHAR-CI< x y) will return #t if x is less
X                than y.  Case is not significant.  #A matchs #a.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME              INPUT/OUTPUT FUNCTIONS              Page 34
X
X
X            INPUT/OUTPUT FUNCTIONS
X
X            (READ [port])
X
X                Reads an expression from the specified port.  If no port
X                is specified, the current input port is used.  Returns
X                the expression read or an object that satisfies the
X                default-object? predicate if it reaches the end of file
X                on the port.
X
X            (READ-CHAR [port])
X
X                Reads a character from the specified port.  If no port
X                is specified, the current input port is used.  Returns
X                the character read or an object that satisfies the
X                default-object? predicate if it reaches the end of file
X                on the port.
X
X            (READ-BYTE [port])
X
X                Reads a byte from the specified port.  If no port is
X                specified, the current input port is used.  Returns the
X                byte read or an object that satisfies the default-
X                object? predicate if it reaches the end of file on the
X                port.
X
X            (WRITE expr [port])
X            (PRIN1 expr [port])
X
X                Writes an expression to the specified port.  If no port
X                is specified, the current output port is used.  The
X                expression is written such that the READ function can
X                read it back.  This means that strings will be enclosed
X                in quotes and characters will be printed with #
X                notation.
X
X            (WRITE-CHAR ch [port])
X
X                Writes a character to the specified port.  If no port is
X                specified, the current output port is used.
X
X            (WRITE-BYTE ch [port])
X
X                Writes a byte to the specified port.  If no port is
X                specified, the current output port is used.
X
X            (DISPLAY expr [port])
X            (PRINC expr [port])
X
X                Writes an expression to the specified port.  If no port
X                is specified, the current output port is used.  The
X                expression is written without any quoting characters.
X                No quotes will appear around strings and characters are
X                written without the # notation.
X
X
X
X
X
X
X
X
X
X        XSCHEME              INPUT/OUTPUT FUNCTIONS              Page 35
X
X
X            (NEWLINE [port])
X
X                Starts a new line on the specified port.  If no port is
X                specified, the current output port is used.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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X
X
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X
X
X
X
X
X
X        XSCHEME             OUTPUT CONTROL FUNCTIONS             Page 36
X
X
X            OUTPUT CONTROL FUNCTIONS
X
X            (PRINT-BREADTH [n])
X
X                Controls the maximum number of elements of a list that
X                will be printed.  If n is an integer, the maximum number
X                is set to n.  If it is #f, the limit is set to infinity.
X                This is the default.  If n is omitted from the call, the
X                current value is returned.
X
X            (PRINT-DEPTH [n])
X
X                Controls the maximum number of levels of a nested list
X                that will be printed.  If n is an integer, the maximum
X                number is set to n.  If it is #f, the limit is set to
X                infinity.  This is the default.  If n is omitted from
X                the call, the current value is returned.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                FILE I/O FUNCTIONS                Page 37
X
X
X            FILE I/O FUNCTIONS
X
X            All four of the following OPEN functions take an optional
X            argument to indicate that file I/O is to be done in binary
X            mode.  For binary files, this argument should be the symbol
X            BINARY.  For text files, the argument can be left out or the
X            symbol TEXT can be supplied.
X
X            (OPEN-INPUT-FILE str ['binary])
X
X                Opens the file named by the string and returns an input
X                port.
X
X            (OPEN-OUTPUT-FILE str ['binary])
X
X                Creates the file named by the string and returns an
X                output port.
X
X            (OPEN-APPEND-FILE str ['binary])
X
X                Opens the file named by the string for appending returns
X                an output port.
X
X            (OPEN-UPDATE-FILE str ['binary])
X
X                Opens the file named by the string for input and output
X                and returns an input/output port.
X
X            (GET-FILE-POSITION port)
X
X                Returns the current file position as an offset in bytes
X                from the beginning of the file.
X
X            (SET-FILE-POSITION! port offset whence)
X
X                Sets the current file position as an offset in bytes
X                from the beginning of the file (when whence equals 0),
X                the current file position (when whence equals 1) or the
X                end of the file (when whence equals 2).  Returns the new
X                file position as an offset from the start of the file.
X
X            (CLOSE-PORT port)
X
X                Closes any port.
X
X            (CLOSE-INPUT-PORT port)
X
X                Closes an input port.
X
X            (CLOSE-OUTPUT-PORT port)
X
X                Closes an output port.
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                FILE I/O FUNCTIONS                Page 38
X
X
X            (CALL-WITH-INPUT-FILE str proc)
X
X                Open the file whose name is specifed by str and call
X                proc passing the resulting input port as an argument.
X                When proc returns, close the file and return the value
X                returned by proc as the result.
X
X            (CALL-WITH-OUTPUT-FILE str proc)
X
X                Create the file whose name is specifed by str and call
X                proc passing the resulting output port as an argument.
X                When proc returns, close the file and return the value
X                returned by proc as the result.
X
X            (CURRENT-INPUT-PORT)
X
X                Returns the current input port.
X
X            (CURRENT-OUTPUT-PORT)
X
X                Returns the current output port.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 CONTROL FEATURES                 Page 39
X
X
X            CONTROL FEATURES
X
X            (EVAL expr)
X
X                Evaluate the expression in the global environment and
X                return its value.
X
X            (APPLY proc args)
X
X                Apply the procedure to the list of arguments and return
X                the result.
X
X            (MAP proc list...)
X
X                Apply the procedure to argument lists formed by taking
X                corresponding elements from each list.  Form a list from
X                the resulting values and return that list as the result
X                of the MAP call.
X
X            (FOR-EACH fun list...)
X
X                Apply the procedure to argument lists formed by taking
X                corresponding elements from each list.  The values
X                returned by the procedure applications are discarded.
X                The value returned by FOR-EACH is unspecified.
X
X            (CALL-WITH-CURRENT-CONTINUATION proc)
X            (CALL/CC proc)
X
X                Form an "escape procedure" from the current continuation
X                and pass it as an argument to proc.  Calling the escape
X                procedure with a single argument will cause that
X                argument to be passed to the continuation that was in
X                effect when the CALL-WITH-CURRENT-CONTINUATION procedure
X                was called.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME              ENVIRONMENT FUNCTIONS               Page 40
X
X
X            ENVIRONMENT FUNCTIONS
X
X            (THE-ENVIRONMENT)
X
X                Returns the current environment.
X
X            (PROCEDURE-ENVIRONMENT proc)
X
X                Returns the environment from a procedure closure.
X
X            (ENVIRONMENT-BINDINGS env)
X
X                Returns an association list corresponding to the top
X                most frame of the specified environment.
X
X            (ENVIRONMENT-PARENT env)
X
X                Returns the parent environment of the specified
X                environment.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                UTILITY FUNCTIONS                 Page 41
X
X
X            UTILITY FUNCTIONS
X
X            (LOAD str)
X
X                Read and evaluate each expression from the specified
X                file.
X
X            (LOAD-NOISILY str)
X
X                Read and evaluate each expression from the specified
X                file and print the results to the current output port.
X
X            (TRANSCRIPT-ON str)
X
X                Opens a transcript file with the specified name and
X                begins logging the interactive session to that file.
X
X            (TRANSCRIPT-OFF)
X
X                Closes the current transcript file.
X
X            (EXIT)
X
X                Exits from XScheme back to the operating system.
X
X            (GC [ni vi])
X
X                Invokes the garbage collector and returns information on
X                memory usage.  If ni and vi are specified, they must be
X                integers.  Node and vector space are expanded by those
X                amounts respectively and no garbage collection is
X                triggered.  GC returns an array of six values: the
X                number of calls to the garbage collector, the total
X                number of nodes, the current number of free nodes, the
X                number of node segments, the number of vector segments
X                and the total number of bytes allocated to the heap.
X
X            (RESET)
X
X                Returns to the top level read/eval/print loop.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME                 SYSTEM FUNCTIONS                 Page 42
X
X
X            SYSTEM FUNCTIONS
X
X            (%CAR pair)
X            (%CDR pair)
X            (%SET-CAR! pair expr)
X            (%SET-CDR! pair expr)
X            (%VECTOR-LENGTH vect)
X            (%VECTOR-REF vect n)
X            (%VECTOR-SET! vect n expr)
X
X                These functions do the same as their counterparts
X                without the leading '%' character.  The difference is
X                that they don't check the type of their first argument.
X                This makes it possible to examine data structures that
X                have the same internal representation as pairs and
X                vectors.  It is *very* dangerous to modify objects using
X                these functions and there is no guarantee that future
X                releases of XScheme will represent objects in the same
X                way that the current version does.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X        XSCHEME              OBJECT REPRESENTATIONS              Page 43
X
X
X                OBJECT REPRESENTATIONS
X
X                This version of XScheme uses the following object
X                representations:
X
X                    Closures are represented as pairs.  The car of the
X                    pair is the compiled function and the cdr of the
X                    pair is the saved environment.
X
X                    Compiled functions are represented as vectors.  The
X                    element at offset 0 is the bytecode string.  The
X                    element at offset 1 is the function name.  The
X                    element at offset 2 is a list of names of the
X                    function arguments.  The elements at offsets above 2
X                    are the literals refered to by the compiled
X                    bytecodes.
X
X                    Environments are represented as lists of vectors.
X                    Each vector is an environment frame.  The element at
X                    offset 0 is a list of the symbols that are bound in
X                    that frame.  The symbol values start at offset 1.
X
X                    Objects are represented as vectors.  The element at
X                    offset 0 is the class of the object.  The remaining
X                    elements are the object's instance variable values.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
END_OF_FILE
if test 52550 -ne `wc -c <'xscheme.doc'`; then
    echo shar: \"'xscheme.doc'\" unpacked with wrong size!
fi
# end of 'xscheme.doc'
fi
echo shar: End of archive 7 \(of 7\).
cp /dev/null ark7isdone
MISSING=""
for I in 1 2 3 4 5 6 7 ; do
    if test ! -f ark${I}isdone ; then
    MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 7 archives.
    rm -f ark[1-9]isdone
else
    echo You still need to unpack the following archives:
    echo "        " ${MISSING}
fi
##  End of shell archive.
exit 0
--
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