rpn v0.7.2

Interpreting calculator using Reverse Polish Notation.

Invocation

usage: rpn.py [-h] [-i] [-s SESSION] [-S] [filenames ...]

Interpreting calculator using Reverse Polish Notation.

positional arguments:
  filenames             Names of RPN script files to execute. If none, then
                        interactive mode.

options:
  -h, --help            show this help message and exit
  -i, --interactive     After executing files, leave in interactive mode.
  -s SESSION, --session SESSION
                        Session file to run first at startup and dump to at
                        exit.
  -S, --autosession     Use the session file defined by environment variable
                        RPN_SESSION_FILE.

Operators

General

Operator	Description	Stack
def	Create a variable in the current keyspace. A variable is a keyed item (value, array, procedure).	key item → -
del	Delete a variable from the current keyspace. If no such variable, then no effect.	key → -
run	Open a new input file, read items from it and execute.	filename → -
count	Count the number of elements in the stack, and put that integer on the stack.	→ integer
dump	Write out the current stack and keyspaces to the named file.	filename → -
quit	Quit from execution without saving to any session file.	N/A

Stack

Operator	Description	Stack
pop	Pop the top item from the stack, and print if interactive.	item → -
dup	Duplicate the top item. A full copy is created.	item → item item
exch	Exchange the two top items on the stack.	item1 item2 → item2 item1
clear	Clear all items from the stack.	... → <empty>
print	Pop the top value and print it.	item → -

Control

Operator	Description	Stack
if	Conditional execution of a procedure.	bool procedure → -
ifelse	Conditional execution of one of two procedures. If bool is true, the first procedure is executed, else the second.	bool procedure1 procedure2 → -
loop	Infinite loop over the procedure. Use operator 'exit' to quit it.	procedure → -
repeat	Repeat the procedure a number of times.	n procedure → -
for	Loop the procedure from the initial number using the increment up to and including the limit. The loop number is pushed each time onto the stack before the procedure is executed.	initial increment limit procedure → value
exit	Exit the innermost loop. In none, then no action.	-

Logic

Operator	Description	Stack
bool	Convert the value to Bool; 0, 0.0, "" and [] are false, other values true.	value → bool
not	Boolean 'not'.	bool → bool
and	Boolean 'and'.	bool1 bool2 → bool
or	Boolean 'or'.	bool1 bool2 → bool
xor	Boolean 'xor' (exclusive or).	bool1 bool2 → bool
gt	Greater than; value1 > value2. The values must of comparable types.	value2 value1 → bool
ge	Greater than or equal to; value1 >= value2. The values must of comparable types.	value2 value1 → bool
lt	Less than; value1 < value2. The values must of comparable types.	value2 value1 → bool
le	Less than or equal to; value1 <= value2. The values must of comparable types.	value2 value1 → bool
eq	Equal to; value1 == value2.	value1 value2 → bool
ne	Not equal to; value1 != value2.	value1 value2 → bool

Numbers

Operator	Description	Stack
integer	Convert the value to an integer.	value → integer
round	Convert the value to the nearest integer.	value → integer
float	Convert the value to a float.	value → float
abs	Absolute value of the number.	number → number
neg	Negate the number.	number → number

Math

Operator	Description	Stack
add	Add the two numbers on the stack. Also available as '+'.	number1 number2 → number
sub	Subtract the top number on the stack from the next-to-top number; number1 - number2. Also available as '-'.	number1 number2 → number
mul	Multiply the two numbers on the stack. Also available as '*'.	number1 number2 → number
div	Divide the next-to-top number on the stack by the top number; number1 / number2. Also available as '/'.	number1 number2 → float
log	Natural logarithm of the number.	number → float
log10	Base-10 logarithm of the number.	number → float
exp	'e' raised to the power of the number.	number → float
power	The next-to-top number to the power of the top number; number1 ^ number2.	number1 number2 → number
sqrt	Square root of the number.	number → float

Trigonometry

Operator	Description	Stack
cos	Cosine of the number (radians).	number → float
sin	Sine of the number (radians).	number → float
tan	Tangent of the number (radians).	number → float
acos	Arc cosine of the number (radians).	number → float
asin	Arc sine of the number (radians).	number → float
atan	Arc tangent of the number (radians).	number → float
atan2	Arc tangent of the next-to-top number divided by the top number (radians).	number1 number2 → float
degrees	Convert the number in radians to degrees.	number → float
radians	Convert the number in degrees to radians.	number → float

Others

Operator	Description	Stack
noop	No operation.	No change.
length	Return length of the item (String, Array).	item → integer
error	Raise an error.	No change.

Interactive

The following one-character operators are available only in interactive mode.

Operator	Description	Stack
=	Print the stack.	No change.
§	Print the keyspaces.	No change.
?	Print the operators.	No change.

Predefined variables

• e: 2.718281828459045
• pi: 3.141592653589793

Demo

# Script testing rpn.

/equality_check {eq {"OK" print} {"Error!" print} ifelse} def

/double {2 mul} def

3 double 6 equality_check
# > OK

-2 double -4 equality_check
# > OK

-2 double 4 equality_check
# > Error!