path

Section: PATH Programming Language (1)
Updated: February 2004
Index

NAME

path - PATH programming language

SYNOPSIS

path [ -dhn ] [ -p dir ] file ...

DESCRIPTION

PATH is a unique two-dimensional programming language. Unlike conventional programming languages, which read a program in left-to-right, top-to-bottom, PATH programs can go up, down, left, and right, and change directions at will. The capabilities of the language can also be extended through the use of plugins.

OPTIONS

-d --debug: Print out extra information about program execution to stderr.
-h --help: Display a help screen and quit.
-n --noplugins: Don't load any plugins.
-p dir --plugindir dir: Load plugins from the directory dir instead of the default location.

FILES

/usr/lib/path/

: System-wide directory for PATH plugins. Plugins for all users go here.

~/.path/

: User-specific directory for PATH plugins. Individual users may place plugins here.

LANGUAGE REFERENCE

A PATH program has only a minimal environment to run: an array of unlimited integers ("memory cells"), and standard input and output. The program can input and/or ouput ASCII values from the cells, increment/decrement cells, seek between different cells, and branch off in different directions if the current cell is not equal to 0. The PATH interpreter starts at the first "$" character in the program file and starts heading right, reading every character (or instruction symbol ) in its way. The interpreter behaves accordingly when it encounters one of these valid instruction symbols:

$ - Start the program here, heading right.
# - End the program.
+ - Increment the current memory cell.
- - Decrement the current memory cell.
} - Move to the next memory cell.
{ - Move to the previous memory cell.
, - Input an ASCII character from standard input into the current memory cell.
. - Output an ASCII character from the current memory cell into standard output.
/ - If heading in direction:
       right, turn up
       down, turn left
       left, turn down
       up, turn right
\\ - If heading in direction:
       right, turn down
       down, turn right
       left, turn up
       up, turn left
^ - If the value of the current memory cell is not 0, turn up.
< - If the value of the current memory cell is not 0, turn left.
> - If the value of the current memory cell is not 0, turn right.
v - If the value of the current memory cell is not 0, turn down.
! - Jump over the next symbol.

If the PATH interpreter does not understand a symbol, it simply passes over it without taking any action. Plugins may also add additional symbols with extra functionality.

AUTHOR

Francis Rogers <exorcismtongs AT users DOT sf DOT net>

This document was created by man2html, using the manual pages (and tweaked by francis).
Time: 00:37:47 GMT, February 25, 2004