Sib-pair Command: eval

Class	Global
Name	eval
Arguments	[Scheme expression]

Accesses the Scheme read-eval-print-loop. If called without arguments, presents the Scheme prompt "%%", otherwise evaluates the rest of the line as if it were a Scheme expression. Sib-pair macro variables and functions are stored within the Scheme environment, and so can read and written to. The Sib-pair specific extensions to Scheme are "(nloci)", "(ls)", "(loc)", "(loctyp)", "(locord)", "(locnotes)", "(read-line)", "(run)" and "(help)".

(ls ["m" | "x" | "h" | "a" | "q" | "d[mxhqa]"])	List locus names
(nloci)	returns total number of loci
(loc )	returns locus at that position in the locus list
(locord <loc>)	returns position of a locus in the locus list
(locnotes <loc>)	returns notes for a locus
(loctyp <loc>)	evaluates type of a locus ("adhmqx")
(read-line <port>)	Read next line from port as a string
(run "<Sib-pair command>")	Run a Sib-pair command
(string-split <string> [<sep>]	Convert from string to list of words split on white-space (or a specified character separator)
(system "<operating system command>")	Run an OS command
(help)	Information about this Scheme implementation

For documentation of other Scheme commands, see the Scheme standard: Standard Revised^5 Report on the Algorithmic Language Scheme (R5RS). The Sib-pair Scheme interpreter is fairly minimal in that it does not implement characters, vectors, noninteger numbers (exact or inexact) or hygienic macros. Aside from this, most of the R5RS examples work without problems (the interpreter is a port of Minischeme/Tinyscheme to Fortran 95).

Example:

>> eval  
%% (define  (interval-list m n)
  (if (> m n)
      '()
      (cons m (interval-list (+ 1 m) n))))
(define (sieve l)
  (define (remove-multiples n l)
    (if (null? l)
        '()
        (if  (= (modulo (car l) n) 0)      ; division test
             (remove-multiples n (cdr l))
             (cons (car l)
                   (remove-multiples n (cdr l))))))
  (if (null? l)
      '()
      (cons (car l)
            (sieve (remove-multiples (car l) (cdr l))))))
(define (primes<= n)
  (sieve (interval-list 2 n)))
%% (primes<= 300)
(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 
101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 
193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293)
%% (quit)
Leaving scheme!
>> eval (primes<= 30)
(2 3 5 7 11 13 17 19 23 29)
>>

Scheme keywords:

<	Numerically less than
<=	Numerically less than or equal
=	Numerically equal
>	Numerically greater than
>=	Numerically greater than or equal to
-	Integer subtraction
/	Integer division
*	Integer multiplication
+	Integer addition
abs	Absolute value
and	Logical and
append	Append to end of list
apply	Apply function to list
apropos	List matching functions
assoc	Find matching pair in an "alist" (list of paired values) using equal?
assq	Find matching pair in an "alist" using eq?
assv	Find matching pair in an "alist" using eqv?
atom?	Is a simple number or string?
begin	Start a block
boolean?	Is a boolean?
car	First element of pair or list
cdr	Remainder of pair or list
caar	First element of first element of pair or list
cadr	Und so weiter
cdar
cddr
caaar
cdddr
caadr
cadar
caddr
cdaar
cdadr
cddar
call/cc	non-local exit from loop or procedure body
call-with-current-continuation	non-local exit from loop or procedure body
case	Conditional branching
closure?	Is a closure
close-input-port	Closes a port
cond	Conditional branching
cons	Create a Lisp pair of elements
cons-stream
define	Define a variable or function
delay	Delay (lazy) evaluation
display	Print a variable or function
else	Default arm of a cond
eq?	Fussy version of eqv? (same memory location)
equal?	Recursively applies eqv?
eqv?	True if obj1 and obj2 should normally be regarded as the same object.
error	Print an error message
eval	Evaluate a SEXPR (Scheme expression)
even?	Test if even
exit	Exit Sib-pair completely
expt	Integer exponentiation
force	Carry out a delayed evaluation
for-each	Like map, but used for side-effects only
gc	Force a garbage collection
gcd	Greatest common divisor
get-closure-code
help	Minimal information about Scheme
if	Conditional branching
integer?	Is an integer
lambda	Function
lcm	Least common multiple
length	Gives length of a list
let	Declare local variables
let*	Declare local variables sequentially
letrec	Declare local variables, allowing recursive definitions
list	Create a list
list-ref	Gives Nth element of a list
list-tail	Drops the first k elements of a list
loctyp	Evaluates type of a Sib-pair locus
ls	List Sib-pair variables
macro
make-string	Create a string of given length
map	Apply a function to each element of a list in turn
max	Maximum of arguments
member	Test if present in a list
memq	Test if present in a list using equal?
memv	Test if present in a list using eqv?
min	Minimum of arguments
modulo	Give modulo
negative?	Test if negative integer
newline	Print a newline
new-segment	Memory allocation chunk size
not	Logical negation
null?	Test if a null
number?	Test if an integer number
number->string	Convert from number to string
odd?	Test if odd
open-input-file	Open an input stream (port)
or	Logical or
pair?	Test if a Lisp pair
positive?	Test if a positive integer
procedure?	Is a function?
quasiquote
quit	Leave the Scheme interpreter
quote	Quoted expression left unevaluated
quotient	Integer division
random	A random integer from U(1, N)
read	Read an Scheme object from input
remainder	Remainder
reverse	Reverse ordering of a list
run	Run a Sib-pair command
set!	Set the contents of an existing variable
set-car!	Set contents of first element of pair or list
set-cdr!	Set contents of rest of pair or list
sqrt	Integer square root
string?	Is argument a string?
string-append	Concatenate strings
string-length	Length of argument string
string-set!	Set the value of a substring
string->number	Convert from a string to a number
string->symbol	Convert from a string to a symbol
substring	Get the value of a substring
string-split	Convert from string to list of words
string=?	Are strings equal?
substring?	Is string 1 a substring of string 2?
string<?	Is string lexicographically less?
string>?	Is string lexicographically greater?
string<=?	Is string lexicographically less than or equal?
string>=?	Is string lexicographically greater than or equal?
symbol?	Is a symbol?
symbol->string	Convert from a symbol to a string
system	Passes commands to the operating system
unquote
unquote-splicing
write	Write a Scheme object
zero?	Test if equal to zero