A dc-like command-like calculator written in Rust
As a desk calculator:
$ rsc -c '3.45 7.82 + .'
11.27
As a pipe component:
$ ...stuff... | rsc '$0 $2 * $1 + .' | ...other stuff...
rsc implements a minimal stack-based language as its base.
Everything in a program is either a literal, a function call, a variable invocation, or an assignment.
The only data type in rsc is a 64-bit floating point number. They are written exactly how you'd expect:
1.2
.07
42
-9
-3.14
-.105
All of the above are valid literals.
Functions manipulate the stack. Below is a list of all functions currently available in rsc.
| Name | Description | Stack transform) |
|---|---|---|
+ |
Adds two numbers | a b -- c |
- |
Subtracts two numbers | a b -- c |
* |
Multiplies two numbers | a b -- c |
/ |
Divides two numbers | a b -- c |
^ |
Raises one number to the power of another | a b -- c |
sqrt |
Takes the square root of a number | a -- b |
exp |
Raises Euler's number e to the power of a number | a -- b |
= |
Tests if two numbers are equal | a b -- p |
< |
Tests if a number is less than another | a b -- p |
> |
Tests if a number is greater than another | a b -- p |
<= |
Tests if a number is less than or equal to another | a b -- p |
>= |
Tests if a number is greater than or equal to another | a b -- p |
? |
Pushes the second value on the stack if the third value down is nonzero, otherwise the top value | p t f -- t/f |
. |
Prints a number to standard output | a -- |
Variables are referenced by prepending a $ to their name, like so: $var.
When invoked, they place their value on the stack.
You can create your own variables using the : operator.
: pops the top value off the stack and assigns it to the variable immediately following it.
For example, this is how you would set x to 3:
3 :x
You could then use $x later in the program.
If not invoked in calculator (-c) mode,
rsc automatically reads a whitespace-separated set of numbers from standard input
and lets you use them by putting a number after $, with the values starting at zero.
For example, this is how you would print the second value from stdin:
$1 .
Note that you cannot assign to arguments; :3, while a cute smiley face, is a syntax error.
There are a few "constants" pre-defined. I place "constants" in quotes because you can redefine them if you really want to. They are enumerated below.
| Name | Mathematical name | Approximate value |
|---|---|---|
E |
e | 2.7183 |
PI |
π | 3.1415 |