Non-interactive mode

If an expression is provided, clac will process it and print each element in the stack starting from the top. It will then exit immediately.

Commands

When a command requires an argument, it pops a value from the stack. If the stack is empty, a zero is provided instead. In the descriptions below, the top of the stack (and thus the first value popped) is represented by the letter `a`, while the second value popped is represented by the letter `b`. For example, if the stack is composed of the number `1`, `2` and `3` (with `3` at the top of the stack), when we describe the sum then `a` will be `3` and `b` will be `2`. It is important to note that subtraction and division invert the order of the arguments before performing the operation: with `1`, `2` and `3` in the stack, when you type `-` it will pop the values `3` and `2` and push the result of `2 - 3`. This is in the tradition of other postfix calculators and programming languages. A description of the available commands follows.

Arithmetic operations

+

Pop two values `a` and `b` and push the result of `a + b`.

-

Pop two values `a` and `b` and push the result of `b - a`.

*

Pop two values `a` and `b` and push the result of `a * b`.

/

Pop two values `a` and `b` and push the result of `b / a`.

Modulo operation

%

Pop two values `a` and `b` and push the remainder of the Euclidean division of `b` by `a`.

Exponentiation

^

Pop two values `a` and `b` and push the result of `b ^ a`.

Logarithm

ln

Pop the value `a` and push its natural logarithm.

log

Pop the value `a` and push its logarithm to base 10.

Factorial

!

Pop the value `a` and push its factorial.

Trigonometry

sin

Pop the value `a` and push its sine.

cos

Pop the value `a` and push its cosine.

tan

Pop the value `a` and push its tangent.

asin

Pop the value `a` and push its arc sine.

acos

Pop the value `a` and push its arc cosine.

atan

Pop the value `a` and push its arc tangent.

atan2

Pop two values `a` and `b` and push the arc tangent of `b / a`, using the signs of `a` and `b` to determine the quadrant.

Error function

erf

Pop the value `a` and push its error function.

Summation

sum

Pop all the values in the stack and push their sum.

add

Pop the value `a` and remove that many items from the stack. Push their sum.

Rounding

ceil

Pop the value `a` and push the smallest integer value greater than or equal to `a`.

floor

Pop the value `a` and push the largest integer value less than or equal to `a`.

round

Pop the value `a` and push the integer value closest to `a`.

Absolute value

abs

Pop the value `a` and push the non-negative value of `a`.

Stack manipulation

swap

Pop two values `a` and `b` and push the values `a`, `b`.

dup

Pop the value `a` and push the values `a`, `a`.

roll

Pop two values `a` and `b` and rotate `b` elements in the stack `a` times.

drop

Remove the top of the stack.

clear

Remove all the elements in the stack.

count

Push the number of items in the stack.

_

Push on the stack the result of the last operation.

Stashing

stash

Pop the value `a` and move that many items to the stash.

fetch

Pop the value `a` and move that many items from the stash.

.

Stash the top of the stack.

,

Fetch one stashed item.

:

Stash all the items in the stack.

;

Fetch all stashed items.

History

Use ⟨C-p⟩ / ⟨C-n⟩ or ⟨Up⟩ / ⟨Down⟩ to navigate the history.

User defined operations

It is possible to define operations (or words, as they are usually called in stack based programming languages) by editing the words configuration file. It is not created by default, but clac will use some environment variables in order to search for word definitions.

$CLAC_WORDS

If set, it should point to a file containing word definitions.

$XDG_CONFIG_HOME

If set, clac will search for $XDG_CONFIG_HOME/clac/words

$HOME

If set, clac will search for $HOME/.config/clac/words

How to define words

Words are defined as aliases, with one alias on each line. Empty lines are ignored. Here are some examples:

Note that an alias has two parts: a word to be defined and its meaning. That's why the tau and sqrt definitions are enclosed in double quotes. If the double quotes are removed, clac will complain that it can't parse the command. For example, if we remove the double quotes from sqrt and start clac, we will get this error message:

User defined words can be used as if they were built-in commands:

How to list defined words

If you type `words` and hit enter, clac will list the defined words.

How to reload defined words

If you type `reload` and hit enter, clac will reload the words file.