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XLISP: An Experimental Object Oriented Language
Version 1.2
October 11, 1984
by
David Betz
114 Davenport Ave.
Manchester, NH 03103
(603) 625-4691 (home)
XLISP: An Experimental Object Oriented Language Page 2
TABLE OF CONTENTS
1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . 3
2.0 A NOTE FROM THE AUTHOR . . . . . . . . . . . . . . . 4
3.0 XLISP COMMAND LOOP . . . . . . . . . . . . . . . . . 5
4.0 DATA TYPES . . . . . . . . . . . . . . . . . . . . . 6
5.0 THE EVALUATOR . . . . . . . . . . . . . . . . . . . 7
6.0 LEXICAL CONVENTIONS . . . . . . . . . . . . . . . . 8
7.0 OBJECTS . . . . . . . . . . . . . . . . . . . . . . 9
8.0 SYMBOLS . . . . . . . . . . . . . . . . . . . . . 12
9.0 EVALUATION FUNCTIONS . . . . . . . . . . . . . . . 13
10.0 SYMBOL FUNCTIONS . . . . . . . . . . . . . . . . . 14
11.0 PROPERTY LIST FUNCTIONS . . . . . . . . . . . . . 15
12.0 LIST FUNCTIONS . . . . . . . . . . . . . . . . . . 16
13.0 DESTRUCTIVE LIST FUNCTIONS . . . . . . . . . . . . 18
14.0 PREDICATE FUNCTIONS . . . . . . . . . . . . . . . 19
15.0 CONTROL FUNCTIONS . . . . . . . . . . . . . . . . 20
16.0 ARITHMETIC FUNCTIONS . . . . . . . . . . . . . . . 22
17.0 BITWISE LOGICAL FUNCTIONS . . . . . . . . . . . . 23
18.0 RELATIONAL FUNCTIONS . . . . . . . . . . . . . . . 24
19.0 STRING FUNCTIONS . . . . . . . . . . . . . . . . . 25
20.0 INPUT/OUTPUT FUNCTIONS . . . . . . . . . . . . . . 26
21.0 FILE I/O FUNCTIONS . . . . . . . . . . . . . . . . 27
22.0 SYSTEM FUNCTIONS . . . . . . . . . . . . . . . . . 28
XLISP: An Experimental Object Oriented Language Page 3
INTRODUCTION
1.0 INTRODUCTION
XLISP is an experimental programming language combining some
of the features of LISP with an object oriented extension
capability. It was implemented to allow experimentation
with object oriented programming on small computers. There
are currently implementations running on the PDP-11 under
RSX-11, RT-11, and UNIX V7, on the VAX-11 under VAX/VMS and
Berkeley VAX/UNIX, on the Z-80 under CP/M-80, on the Z8000
under UNIX V7, and on the 8088/8086 under CP/M-86 or MS-DOS.
A version is currently being developed for the 68000 under
CP/M-68K. It is completely written in the programming
language 'C' and is easily extended with user written
built-in functions and classes. It is available in source
form free of charge to non-commercial users. Prospective
commercial users should contact the author for permission to
use XLISP.
Many traditional LISP functions are built into XLISP. In
addition, XLISP defines the objects 'Object' and 'Class' as
primitives. 'Object' is the only class that has no
superclass and hence is the root of the class heirarchy
tree. 'Class' is the class of which all classes are
instances (it is the only object that is an instance of
itself).
This document is intended to be a brief description of
XLISP. It assumes some knowledge of LISP and some
understanding of the concepts of object oriented
programming.
Version 1.2 of XLISP differs from version 1.1 in several
ways. It supports many more Lisp functions. Also, many
version 1.1 functions have been renamed and/or changed
slightly to follow traditional Lisp usage. One of the most
frequently reported problems in version 1.1 resulted from
many functions being named after their equivilent functions
in the C language. This turned out to be confusing for
people who were trying to learn XLISP using traditional LISP
texts as references. Version 1.2 renames these functions to
be compatible with more traditional dialects of LISP.
A recommended text for learning LISP programming is the book
"LISP" by Winston and Horn and published by Addison Wesley.
The first edition of this book is based on MacLisp and the
second edition is based on Common Lisp. Future version of
XLISP will migrate towards compatiblility with Common Lisp.
XLISP: An Experimental Object Oriented Language Page 4
A NOTE FROM THE AUTHOR
2.0 A NOTE FROM THE AUTHOR
If you have any problems with XLISP, feel free to contact me
for help or advice. Please remember that since XLISP is
available in source form in a high level language, many
users have been making versions available on a variety of
machines. If you call to report a problem with a specific
version, I may not be able to help you if that version runs
on a machine to which I don't have access.
If you find a bug in XLISP, first try to fix the bug
yourself using the source code provided. If you are
successful in fixing the bug, send the bug report along with
the fix to me. If you don't have access to a C compiler or
are unable to fix a bug, please send the bug report to me
and I'll try to fix it.
Any suggestions for improvements will be welcomed. Feel
free to extend the language in whatever way suits your
needs. However, PLEASE DO NOT RELEASE ENHANCED VERSIONS
WITHOUT CHECKING WITH ME FIRST!! I would like to be the
clearing house for new features added to XLISP. If you want
to add features for your own personal use, go ahead. But,
if you want to distribute your enhanced version, contact me
first. Please remember that the goal of XLISP is to provide
a language to learn and experiment with LISP and object
oriented programming on small computers. Version 1.2 barely
fits on a 64K Z-80 running CP/M-80.
XLISP: An Experimental Object Oriented Language Page 5
XLISP COMMAND LOOP
3.0 XLISP COMMAND LOOP
When XLISP is started, it first tries to load "init.lsp"
from the default directory. It then loads any files named
as parameters on the command line (after appending ".lsp" to
their names). It then issues the following prompt:
>
This indicates that XLISP is waiting for an expression to be
typed. When an incomplete expression has been typed (one
where the left and right parens don't match) XLISP changes
its prompt to:
n>
where n is an integer indicating how many levels of left
parens remain unclosed.
When a complete expression has been entered, XLISP attempts
to evaluate that expression. If the expression evaluates
successfully, XLISP prints the result of the evaluation and
then returns to the initial prompt waiting for another
expression to be typed.
Input can be aborted at any time by typing the CONTROL-G key
(it may be necessary to follow CONTROL-G by return).
XLISP: An Experimental Object Oriented Language Page 6
DATA TYPES
4.0 DATA TYPES
There are several different data types available to XLISP
programmers.
o lists
o symbols
o strings
o integers
o objects
o file pointers
o subrs/fsubrs (built-in functions)
Another data type is the stream. A stream is a list node
whose car points to the head of a list of integers and whose
cdr points to the last list node of the list. An empty
stream is a list node whose car and cdr are nil. Each of
the integers in the list represent characters in the stream.
When a character is read from a stream, the first integer
from the head of the list is removed and returned. When a
character is written to a stream, the integer representing
the character code of the character is appended to the end
of the list. When a function indicates that it takes an
input source as a parameter, this parameter can either be an
input file pointer or a stream. Similarly, when a function
indicates that it takes an output sink as a parameter, this
parameter can either be an output file pointer or a stream.
XLISP: An Experimental Object Oriented Language Page 7
THE EVALUATOR
5.0 THE EVALUATOR
The process of evaluation in XLISP:
o Integers, strings, objects, file pointers, and
subrs evaluate to themselves
o Symbols evaluate to the value associated with their
current binding
o Lists are evaluated by evaluating the first element
of the list
o If it evaluates to a subr, the remaining list
elements are evaluated and the subr is called
with these evaluated expressions as arguments.
o If it evaluates to an fsubr, the fsubr is
called using the remaining list elements as
arguments (they are evaluated by the subr
itself if necessary)
o If it evaluates to a list and the car of the
list is 'lambda', the remaining list elements
are evaluated and the resulting expressions are
bound to the formal arguments of the lambda
expression. The body of the function is
executed within this new binding environment.
o If it evaluates to a list and the car of the
list is 'nlambda', the remaining list elements
are bound to the formal arguments of the
nlambda expression. The body of the function
is executed within this new binding
environment.
o If it evaluates to an object, the second list
element is evaluated and used as a message
selector. The message formed by combining the
selector with the values of the remaining list
elements is sent to the object.
XLISP: An Experimental Object Oriented Language Page 8
LEXICAL CONVENTIONS
6.0 LEXICAL CONVENTIONS
The following conventions are followed when entering XLISP
programs:
Comments in XLISP code begin with a semi-colon character and
continue to the end of the line.
Symbol names in XLISP can consist of any sequence of
non-blank printable characters except the following:
( ) . ' " ;
Upper and lower case characters are distinct. The symbols
'CAR' and 'car' are not the same. The names of all built-in
functions are in lower case. The names of all built-in
objects are lower case with an initial capital. Symbol
names must not begin with a digit.
Integer literals consist of a sequence of digits optionally
beginning with a '+' or '-'. The range of values an integer
can represent is limited by the size of a C 'int' on the
machine that XLISP is running on.
Literal strings are sequences of characters surrounded by
double quotes. Within quoted strings the '\' character is
used to allow non-printable characters to be included. The
codes recognized are:
\\ means the character '\'
\n means newline
\t means tab
\r means return
\e means escape
\nnn means the character whose octal code is nnn
The single quote character can be used as a shorthand for a
call on the function 'quote':
'foo
is equivalent to:
(quote foo)
XLISP: An Experimental Object Oriented Language Page 9
OBJECTS
7.0 OBJECTS
Definitions:
o selector - a symbol used to select an appropriate
method
o message - a selector and a list of actual arguments
o method - the code that implements a message
Since XLISP was created to provide a simple basis for
experimenting with object oriented programming, one of the
primitive data types included was 'object'. In XLISP, an
object consists of a data structure containing a pointer to
the object's class as well as a list containing the values
of the object's instance variables.
Officially, there is no way to see inside an object (look at
the values of its instance variables). The only way to
communicate with an object is by sending it a message. When
the XLISP evaluator evaluates a list the value of whose
first element is an object, it interprets the value of the
second element of the list (which must be a symbol) as the
message selector. The evaluator determines the class of the
receiving object and attempts to find a method corresponding
to the message selector in the set of messages defined for
that class. If the message is not found in the object's
class and the class has a super-class, the search continues
by looking at the messages defined for the super-class.
This process continues from one super-class to the next
until a method for the message is found. If no method is
found, an error occurs.
When a method is found, the evaluator binds the receiving
object to the symbol 'self', binds the class in which the
method was found to the symbol 'msgclass', and evaluates the
method using the remaining elements of the original list as
arguments to the method. These arguments are always
evaluated prior to being bound to their corresponding formal
arguments. The result of evaluating the method becomes the
result of the expression.
XLISP: An Experimental Object Oriented Language Page 10
OBJECTS
Classes:
Object THE TOP OF THE CLASS HEIRARCHY
Messages:
show SHOW AN OBJECT'S INSTANCE VARIABLES
returns the object
class RETURN THE CLASS OF AN OBJECT
returns the class of the object
isnew THE DEFAULT OBJECT INITIALIZATION ROUTINE
returns the object
sendsuper <sel> [<args>...] SEND SUPERCLASS A MESSAGE
<sel> the message selector
<args> the message arguments
returns the result of sending the message
XLISP: An Experimental Object Oriented Language Page 11
OBJECTS
Class THE CLASS OF ALL OBJECT CLASSES (including itself)
Messages:
new CREATE A NEW INSTANCE OF A CLASS
returns the new class object
isnew [<scls>] INITIALIZE A NEW CLASS
<scls> the superclass
returns the new class object
answer <msg> <fargs> <code> ADD A MESSAGE TO A CLASS
<msg> the message symbol
<fargs> the formal argument list
this list is of the form:
(<farg>... [&rest <rarg>] [&aux <aux>...])
where
<farg> a formal argument
<rarg> bound to the rest of the arguments
<aux> a auxiliary variable
<code> a list of executable expressions
returns the object
ivars <vars> DEFINE THE LIST OF INSTANCE VARIABLES
<vars> the list of instance variable symbols
returns the object
cvars <vars> DEFINE THE LIST OF CLASS VARIABLES
<vars> the list of class variable symbols
returns the object
When a new instance of a class is created by sending the
message 'new' to an existing class, the message 'isnew'
followed by whatever parameters were passed to the 'new'
message is sent to the newly created object.
When a new class is created by sending the 'new' message to
the object 'Class', an optional parameter may be specified
indicating the superclass of the new class. If this
parameter is omitted, the new class will be a subclass of
'Object'. A class inherits all instance variables, class
variables, and methods from its super-class.
XLISP: An Experimental Object Oriented Language Page 12
SYMBOLS
8.0 SYMBOLS
o self - the current object (within a message
context)
o msgclass - the class in which the current method
was found
o *oblist* - the object list
o *standard-input* - the standard input file
o *standard-output* - the standard output file
o *tracenable* - flag controlling trace back printout
on errors
o *unbound* - indicator for unbound symbols
XLISP: An Experimental Object Oriented Language Page 13
EVALUATION FUNCTIONS
9.0 EVALUATION FUNCTIONS
(eval <expr>) EVALUATE AN XLISP EXPRESSION
<expr> the expression to be evaluated
returns the result of evaluating the expression
(apply <fun> <args>) APPLY A FUNCTION TO A LIST OF ARGUMENTS
<fun> the function to apply (or function symbol)
<args> the argument list
returns the result of applying the function to the argument list
(funcall <fun> <arg>...) CALL A FUNCTION WITH ARGUMENTS
<fun> the function to call (or function symbol)
<arg> arguments to pass to the function
returns the result of calling the function with the arguments
(quote <expr>) RETURN AN EXPRESSION UNEVALUATED
<expr> the expression to be quoted (quoted)
returns <expr> unevaluated
XLISP: An Experimental Object Oriented Language Page 14
SYMBOL FUNCTIONS
10.0 SYMBOL FUNCTIONS
(set <sym> <expr>) SET THE VALUE OF A SYMBOL
<sym> the symbol being set
<expr> the new value
returns the new value
(setq <sym> <expr>) SET THE VALUE OF A SYMBOL
<sym> the symbol being set (quoted)
<expr> the new value
returns the new value
(defun <sym> <fargs> <expr>...) DEFINE A FUNCTION WITH EVALUATED ARGS
(ndefun <sym> <fargs> <expr>...) DEFINE A FUNCTION WITH UNEVALUATED ARGS
<sym> symbol being defined (quoted)
<fargs> list of formal arguments (quoted)
this list is of the form:
(<farg>... [&rest <rarg>] [&aux <aux>...])
where
<farg> is a formal argument
<rarg> bound to the rest of the arguments
<aux> is an auxiliary variable
<expr> expressions constituting the body of the
function (quoted)
returns the function symbol
(gensym <tag>) GENERATE A SYMBOL
<tag> symbol/string/number
returns the new symbol
(intern <sym>) INTERN A SYMBOL ON THE OBLIST
<sym> the symbol
returns the interned symbol
(symbol-name <sym>) GET THE PRINT NAME OF A SYMBOL
<sym> the symbol
returns the symbol's print name
(symbol-plist <sym>) GET THE PROPERTY LIST OF A SYMBOL
<sym> the symbol
returns the symbol's property list
XLISP: An Experimental Object Oriented Language Page 15
PROPERTY LIST FUNCTIONS
11.0 PROPERTY LIST FUNCTIONS
(get <sym> <prop>) GET THE VALUE OF A PROPERTY
<sym> the symbol
<prop> the property symbol
returns the property value or nil
(putprop <sym> <value> <prop>) PUT A PROPERTY ONTO A PROPERTY LIST
<sym> the symbol
<value> the property value
<prop> the property symbol
returns the value
(remprop <prop> <sym>) REMOVE A PROPERTY
<sym> the symbol
<prop> the property symbol
returns nil
XLISP: An Experimental Object Oriented Language Page 16
LIST FUNCTIONS
12.0 LIST FUNCTIONS
(car <expr>) RETURN THE CAR OF A LIST NODE
<expr> the list node
returns the car of the list node
(cdr <expr>) RETURN THE CDR OF A LIST NODE
<expr> the list node
returns the cdr of the list node
(caar <expr>) == (car (car <expr>))
(cadr <expr>) == (car (cdr <expr>))
(cdar <expr>) == (cdr (car <expr>))
(cddr <expr>) == (cdr (cdr <expr>))
(cons <expr1> <expr2>) CONSTRUCT A NEW LIST NODE
<expr1> the car of the new list node
<expr2> the cdr of the new list node
returns the new list node
(list <expr>...) CREATE A LIST OF VALUES
<expr> expressions to be combined into a list
returns the new list
(append <expr>...) APPEND LISTS
<expr> lists whose elements are to be appended
returns the new list
(reverse <expr>) REVERSE A LIST
<expr> the list to reverse
returns a new list in the reverse order
(last <list>) RETURN THE LAST LIST NODE OF A LIST
<list> the list
returns the last list node in the list
(member <expr> <list>) FIND AN EXPRESSION IN A LIST
<expr> the expression to find (equal test)
<list> the list to search
returns the remainder of the list starting with the expression
(memq <expr> <list>) FIND AN EXPRESSION IN A LIST
<expr> the expression to find (eq test)
<list> the list to find it in
returns the remainder of the list starting with the expression
XLISP: An Experimental Object Oriented Language Page 17
LIST FUNCTIONS
(assoc <expr> <alist>) FIND AN EXPRESSION IN AN ASSOCIATION LIST
<expr> the expression to find (equal test)
<alist> the association list
returns the alist entry or nil
(assq <expr> <alist>) FIND AN EXPRESSION IN AN ASSOCIATION LIST
<expr> the expression to find (eq test)
<alist> the association list
returns the alist entry or nil
(length <expr>) FIND THE LENGTH OF A LIST
<expr> the list
returns the length of the list
(nth <n> <list>) RETURN THE NTH ELEMENT OF A LIST
<n> the number of the element to return (zero origin)
<list> the list
returns the nth element or nil if the list isn't that long
(nthcdr <n> <list>) RETURN THE NTH CDR OF A LIST
<n> the number of the element to return (zero origin)
<list> the list
returns the nth cdr or nil if the list isn't that long
(mapcar <fcn> <list1>...<listn>) APPLY FUNCTION TO SUCCESSIVE CARS
<fcn> the function or function name
<list1..n> a list for each argument of the function
returns the list of values returned by each function invocation
(maplist <fcn> <list1>...<listn>) APPLY FUNCTION TO SUCCESSIVE CDRS
<fcn> the function or function name
<list1..n> a list for each argument of the function
returns the list of values returned by each function invocation
(subst <to> <from> <expr>) SUBSTITUTE ONE EXPRESSION FOR ANOTHER
<to> the new expression
<from> the old expression
<expr> the expression in which to do the substitutions
returns the expression with substitutions
(sublis <alist> <expr>) SUBSTITUTE USING AN ASSOCIATION LIST
<alist> the association list
<expr> the expression in which to do the substitutions
returns the expression with substitutions
XLISP: An Experimental Object Oriented Language Page 18
DESTRUCTIVE LIST FUNCTIONS
13.0 DESTRUCTIVE LIST FUNCTIONS
(rplaca <list> <expr>) REPLACE THE CAR OF A LIST NODE
<list> the list node
<expr> the new value for the car of the list node
returns the list node after updating the car
(rplacd <list> <expr>) REPLACE THE CDR OF A LIST NODE
<list> the list node
<expr> the new value for the cdr of the list node
returns the list node after updating the cdr
(nconc <list>...) DESTRUCTIVELY CONCATENATE LISTS
<list> lists to concatenate
returns the result of concatenating the lists
(delete <expr> <list>) DELETE OCCURANCES OF AN EXPRESSION FROM A LIST
<expr> the expression to delete (equal test)
<list> the list
returns the list with the matching expressions deleted
(delq <expr> <list>) DELETE OCCURANCES OF AN EXPRESSION FROM A LIST
<expr> the expression to delete (eq test)
<list> the list
returns the list with the matching expressions deleted
XLISP: An Experimental Object Oriented Language Page 19
PREDICATE FUNCTIONS
14.0 PREDICATE FUNCTIONS
(atom <expr>) IS THIS AN ATOM?
<expr> the expression to check
returns t if the value is an atom, nil otherwise
(symbolp <expr>) IS THIS A SYMBOL?
<expr> the expression to check
returns t if the expression is a symbol, nil otherwise
(numberp <expr>) IS THIS A NUMBER?
<expr> the expression to check
returns t if the expression is a symbol, nil otherwise
(null <expr>) IS THIS AN EMPTY LIST?
<expr> the list to check
returns t if the list is empty, nil otherwise
(not <expr>) IS THIS FALSE?
<expr> the expression to check
return t if the expression is nil, nil otherwise
(listp <expr>) IS THIS A LIST?
<expr> the expression to check
returns t if the value is a list node or nil, nil otherwise
(consp <expr>) IS THIS A NON-EMPTY LIST?
<expr> the expression to check
returns t if the value is a list node, nil otherwise
(boundp <sym>) IS THIS A BOUND SYMBOL?
<sym> the symbol
returns t if a value is bound to the symbol, nil otherwise
(eq <expr1> <expr2>) ARE THE EXPRESSIONS IDENTICAL?
<expr1> the first expression
<expr2> the second expression
returns t if they are equal, nil otherwise
(equal <expr1> <expr2>) ARE THE EXPRESSIONS EQUAL?
<expr1> the first expression
<expr2> the second expression
returns t if they are equal, nil otherwise
XLISP: An Experimental Object Oriented Language Page 20
CONTROL FUNCTIONS
15.0 CONTROL FUNCTIONS
(cond <pair>...) EVALUATE CONDITIONALLY
<pair> pair consisting of:
(<pred> <expr>...)
where
<pred> is a predicate expression
<expr> evaluated if the predicate
is not nil
returns the value of the first expression whose predicate
is not nil
(let (<binding>...) <expr>...) BIND SYMBOLS AND EVALUATE EXPRESSIONS
<binding> the variable bindings each of which is either:
1) a symbol (which is initialized to nil)
2) a list whose car is a symbol and whose cadr
is an initialization expression
<expr>... the expressions to be evaluated with the specified bindings
returns the value of the last expression
(and <expr>...) THE LOGICAL AND OF A LIST OF EXPRESSIONS
<expr>... the expressions to be ANDed
returns nil if any expression evaluates to nil,
otherwise the value of the last expression
(evaluation of expressions stops after the first
expression that evaluates to nil)
(or <expr>...) THE LOGICAL OR OF A LIST OF EXPRESSIONS
<expr>... the expressions to be ORed
returns nil if all expressions evaluate to nil,
otherwise the value of the first non-nil expression
(evaluation of expressions stops after the first
expression that does not evaluate to nil)
(if <texpr> <expr1> [<expr2>]) EXECUTE EXPRESSIONS CONDITIONALLY
<texpr> the test expression
<expr1> the expression to be evaluated if texpr is non-nil
<expr2> the expression to be evaluated if texpr is nil
returns the value of the selected expression
(progn <expr>...) EXECUTE EXPRESSIONS SEQUENTIALLY
<expr>... the expressions to evaluate
returns the value of the last expression
(while <texpr> <expr>...) ITERATE WHILE AN EXPRESSION IS TRUE
<texpr> the test expression evaluated at start of each iteration
<expr>... the expressions evaluated as long as <texpr> evaluates to
non-nil
returns the value of the last expression
XLISP: An Experimental Object Oriented Language Page 21
CONTROL FUNCTIONS
(repeat <iexpr> <expr>...) ITERATE USING A REPEAT COUNT
<iexpr> the integer expression indicating the repeat count
<expr>... the expressions evaluated <iexpr> times
returns the value of the last expression
XLISP: An Experimental Object Oriented Language Page 22
ARITHMETIC FUNCTIONS
16.0 ARITHMETIC FUNCTIONS
(+ <expr>...) ADD A LIST OF NUMBERS
<expr>... the numbers
returns the result of the addition
(- <expr>...) SUBTRACT A LIST OF NUMBERS
<expr>... the numbers
returns the result of the subtraction
(* <expr>...) MULTIPLY A LIST OF NUMBERS
<expr>... the numbers
returns the result of the multiplication
(/ <expr>...) DIVIDE A LIST OF NUMBERS
<expr>... the numbers
returns the result of the division
(1+ <expr>) ADD ONE TO A NUMBER
<expr> the number
returns the number plus one
(1- <expr>) SUBTRACT ONE FROM A NUMBER
<expr> the number
returns the number minus one
(rem <expr>...) REMAINDER OF A LIST OF NUMBERS
<expr>... the numbers
returns the result of the remainder operation
(minus <expr>) NEGATE A NUMBER
<expr> the number
returns the number negated
(min <expr>...) THE SMALLEST OF A LIST OF NUMBERS
<expr>... the expressions to be checked
returns the smallest number in the list
(max <expr>...) THE LARGEST OF A LIST OF NUMBERS
<expr>... the expressions to be checked
returns the largest number in the list
(abs <expr>) THE ABSOLUTE VALUE OF A NUMBER
<expr> the number
returns the absolute value of the number
XLISP: An Experimental Object Oriented Language Page 23
BITWISE LOGICAL FUNCTIONS
17.0 BITWISE LOGICAL FUNCTIONS
(bit-and <expr>...) THE BITWISE AND OF A LIST OF NUMBERS
<expr> the numbers
returns the result of the and operation
(bit-ior <expr...) THE BITWISE INCLUSIVE OR OF A LIST OF NUMBERS
<expr> the numbers
returns the result of the inclusive or operation
(bit-xor <expr...) THE BITWISE EXCLUSIVE OR OF A LIST OF NUMBERS
<expr> the numbers
returns the result of the exclusive or operation
(bit-not <expr>) THE BITWISE NOT OF A NUMBER
<expr> the number
returns the bitwise inversion of number
XLISP: An Experimental Object Oriented Language Page 24
RELATIONAL FUNCTIONS
18.0 RELATIONAL FUNCTIONS
The relational functions can be used to compare integers or
strings. The functions '=' and '/=' can also be used to
compare other types. The result of these comparisons is
computed the same way as for 'eq'.
(< <e1> <e2>) TEST FOR LESS THAN
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
(<= <e1> <e2>) TEST FOR LESS THAN OR EQUAL TO
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
(= <e1> <e2>) TEST FOR EQUAL TO
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
(/= <e1> <e2>) TEST FOR NOT EQUAL TO
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
(>= <e1> <e2>) TEST FOR GREATER THAN OR EQUAL TO
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
(> <e1> <e2>) TEST FOR GREATER THAN
<e1> the left operand of the comparison
<e2> the right operand of the comparison
returns the result of comparing <e1> with <e2>
XLISP: An Experimental Object Oriented Language Page 25
STRING FUNCTIONS
19.0 STRING FUNCTIONS
(strcat <expr>...) CONCATENATE STRINGS
<expr>... the strings to concatenate
returns the result of concatenating the strings
(strlen <expr>) COMPUTE THE LENGTH OF A STRING
<expr> the string
returns the length of the string
(substr <expr> <sexpr> [<lexpr>]) EXTRACT A SUBSTRING
<expr> the string
<sexpr> the starting position
<lexpr> the length (default is rest of string)
returns substring starting at <sexpr> for <lexpr>
(ascii <expr>) NUMERIC VALUE OF CHARACTER
<expr> the string
returns the ascii code of the first character
(chr <expr>) CHARACTER EQUIVALENT OF ASCII VALUE
<expr> the numeric expression
returns a one character string whose first character is <expr>
(atoi <expr>) CONVERT AN ASCII STRING TO AN INTEGER
<expr> the string
returns the integer value of the string expression
(itoa <expr>) CONVERT AN INTEGER TO AN ASCII STRING
<expr> the integer
returns the string representation of the integer value
XLISP: An Experimental Object Oriented Language Page 26
INPUT/OUTPUT FUNCTIONS
20.0 INPUT/OUTPUT FUNCTIONS
(read [<source>[<eof>]]) READ AN XLISP EXPRESSION
<source> the input source (default is standard input)
<eof> the value to return on end of file (default is nil)
returns the expression read
(print <expr> [<sink>]) PRINT A LIST OF VALUES ON A NEW LINE
<expr> the expressions to be printed
<sink> the output sink (default is standard output)
returns nil
(prin1 <expr> [<sink>]) PRINT A LIST OF VALUES
<expr> the expressions to be printed
<sink> the output sink (default is standard output)
returns nil
(princ <expr> [<sink>]) PRINT A LIST OF VALUES WITHOUT QUOTING
<expr> the expressions to be printed
<sink> the output sink (default is standard output)
returns nil
(terpri [<sink>]) TERMINATE THE CURRENT PRINT LINE
<sink> the output sink (default is standard output)
returns nil
(flatsize <expr>) LENGTH OF PRINTED REPRESENTATION USING PRIN1
<expr> the expression
returns the length
(flatc <expr>) LENGTH OF PRINTED REPRESENTATION USING PRINC
<expr> the expression
returns the length
(explode <expr>) CHARACTERS IN PRINTED REPRESENTATION USING PRIN1
<expr> the expression
returns the list of characters
(explodec <expr>) CHARACTERS IN PRINTED REPRESENTATION USING PRINC
<expr> the expression
returns the list of characters
(maknam <list>) BUILD AN UNINTERNED SYMBOL FROM A LIST OF CHARACTERS
<list> list of characters in symbol name
returns the symbol
(implode <list>) BUILD AN INTERNED SYMBOL FROM A LIST OF CHARACTERS
<list> list of characters in symbol name
returns the symbol
XLISP: An Experimental Object Oriented Language Page 27
FILE I/O FUNCTIONS
21.0 FILE I/O FUNCTIONS
(openi <fname>) OPEN AN INPUT FILE
<fname> the file name string
returns a file pointer
(openo <fname>) OPEN AN OUTPUT FILE
<fname> the file name string
returns a file pointer
(close <fp>) CLOSE A FILE
<fp> the file pointer
returns nil
(read-char [<source>]) READ A CHARACTER FROM A FILE OR STREAM
<source> the input source (default is standard input)
returns the character (integer)
(peek-char [<flag> [<source>]]) PEEK AT THE NEXT CHARACTER
<flag> flag for skipping white space (default is nil)
<source> the input source (default is standard input)
returns the character (integer)
(write-char <ch> [<sink>]) WRITE A CHARACTER TO A FILE OR STREAM
<ch> the character to put (integer)
<sink> the output sink (default is standard output)
returns the character (integer)
(readline [<source>]) READ A LINE FROM A FILE OR STREAM
<source> the input source (default is standard input)
returns the input string
XLISP: An Experimental Object Oriented Language Page 28
SYSTEM FUNCTIONS
22.0 SYSTEM FUNCTIONS
(load <fname>) LOAD AN XLISP SOURCE FILE
<fname> the filename string (".lsp" is appended)
returns the filename
(gc) FORCE GARBAGE COLLECTION
returns nil
(expand <num>) EXPAND MEMORY BY ADDING SEGMENTS
<num> the number of segments to add
returns the number of segments added
(alloc <num>) CHANGE NUMBER OF NODES TO ALLOCATE IN EACH SEGMENT
<num> the number of nodes to allocate
returns the old number of nodes to allocate
(mem) SHOW MEMORY ALLOCATION STATISTICS
returns nil
(type <expr>) RETURNS THE TYPE OF THE EXPRESSION
<expr> the expression to return the type of
returns nil if the value is nil otherwise one of the symbols:
SYM for symbols
OBJ for objects
LIST for list nodes
SUBR for subroutine nodes with evaluated arguments
FSUBR for subroutine nodes with unevaluated arguments
STR for string nodes
INT for integer nodes
FPTR for file pointer nodes
(exit) EXIT XLISP
returns never returns
