goclacker

goclacker

• goclacker
  • Installation
  • Usage
  • Interactive mode
  • Prompt
  • Words
    • Value words
  • Configuration
  • License

Command line reverse Polish notation (RPN) calculator. This stack is ready to Go.

By Josh Tompkin

[email protected]

https://github.com/jtompkin/goclacker

Installation

Install with Go.

go install github.com/jtompkin/goclacker@latest

Build with Go.

git clone https://github.com/jtompkin/goclacker.git
cd goclacker
go get -u golang.org/x/term
go build .

Live, laugh, love with Go.

If you are not familiar with Go, the binary will be in ~/go/bin for Linux, C:\users\%username%\go\bin for Windows (probably).

Pre-built binaries are available on the release page.

Usage

goclacker [-V] [-h] [-s] [-d] [-r] [-l] int [-c] string [-p] string [program]...

If any positional arguments (program...) are supplied, they will be interpreted and executed by the calculator. To enter interactive mode, do not provide any arguments to program.... Run goclacker -h to see information about the other command line arguments. If the program does not work, you must first denounce infix notation and your god, and it will then work as intended.

Interactive mode

Type a number and press enter to push it to the stack. Type an operator and press enter to execute that operator on the stack. Enter help to see available operators. Enter multiple commands separated by a space and press enter to execute them in order.

Prompt

If you're in to accessorizing your command line RPN calculators (I know you are), you can create your own custom prompt with the -p flag. Just provide a single string that defines what you want the prompt to look like. If you wanna go really crazy, you can include format specifiers that will print information about your current calculating environment! All format specifiers are prefixed by an & character; some use parameters that come after the & and before the specifier. Some examples:

• goclacker -p ' &c > ' would make a prompt that prints the current stack size and a greater than character. All spaces are preserved; no extra whitespace is ever added. This happens to be the default prompt.

• goclacker -p '-&3t-&l- <3 ' would make a prompt that prints the top 3 values in the stack and the stack size limit surrounded by - characters, and a heart. For when you're in the mood for that reverse Polish goodness.

You can probably break this if you try hard enough, so please do.

Words

Custom commands (called words) can be defined in a config file (see config file if you wanna know how).

You can also define words in interactive mode!! To do so, start your command with = and then type the word and the program you want to run when you enter the word (the > is not typed, ya dingus). Consider entering the following lines at the interactive prompt:

  > = sqrt 0.5 ^
  > = logb log swap log / -1 ^

Now, when sqrt is entered at the prompt, 0.5 is pushed to the stack, and the exponentiation operator is called. That is apparently the same thing as taking the square root. Math is crazy. Similarly, when logb is entered at the prompt, all of the commands in its definition will be executed, effectively popping a and b and pushing the logarithm base b of a.

These two words happen to be automagically defined whenever you start the program. If you hate them (or any other words you define) you can delete a defined word by providing its name after = without any definition. You can also freely redefine any currently defined word.

  > = sqrt
  > = logb

All currently defined words can be viewed by entering words. Words will be separated from their definition by a :.

Value words

You can also define value words by beginning your command with ==. Value words are essentially aliases for numerical values, so instead of executing the commands in the definition, they just push the defined value straight into the stack when entered after they are defined.

  > == pi 22 7 /

This would start a sub-stack, push 22 and 7 to it and call the division operator. It would then set the value of pi to the value at the top of this sub-stack---in this case the only value in the sub-stack.

Value words are separated from their value in the words screen by an =.

Configuration

If you have crafted a beautiful prompt or have a list of words that you can't live without, a config file is what you need. Provide the path to this text file with the -c flag, and it will set the prompt format and execute any additional programs you supply. Goclacker looks for default config files in the following locations and loads the first one it finds:

• ./.goclacker
• ~/.goclacker
• ~/.config/goclacker/config

Passing anything---including an empty string---to -c will disable default config files.

The format is as follows:

• First line is the prompt format.
• All other lines are programs to execute.

The first line is always interpreted as the prompt format. Leave it blank if you want the default prompt. You can surround your format with " on either side if you would like (not '!!); a single pair of surrounding double quotes will not be included in the prompt. If you want a blank prompt (because you are boring), place a single " in the first line. Any format provided with -p will override whatever is in the config file.

Any other lines are interpreted just as if they were entered in interactive mode. Defining words that will be present each time you start the program is the most useful use of this, but any regular calculations can also be done here, if you want certain values to be in your stack at start-up.

A configuration file containing the following lines would set the prompt to look like ------> (notice the lack of " and the preserved whitespace), and define the a word and a value word. It would then push the square root of pi, push the value 2, and call the multiplication operator. These last three lines could all be put on the same line, just like in interactive mode.

------> "
= sqrt 0.5 ^
== pi 3.14159265358979323846
pi sqrt
2
*

License

Licensed under the MIT license. See LICENSE file.