Harp

The Harp programming language is an esoteric programming language by User:Rdococ. It aims to combine the worlds of logic and programming, in a new and unique way.

Structure
Harp is a one-instruction language. At the beginning of the program, it asks for input. Then, every instruction - which has two parameters A and B, and for which the syntax is simply the two parameters, separated by spaces - goes like this:
 * If last input is equal to A, or A is empty
 * Ask for input
 * Execute the instruction at B


 * Otherwise
 * Execute the next instruction

Computational Class
It is designed to be a finite state automaton, but you never know...

Interpreter
Harp interpreter in Lua. Copy into a text document and save as a lua file. Place it in the same directory as the file you want to run, enter the file's name when it asks, and then you can run the program. Output will tell you when the interpreter jumps to a different line. If you type 'exit', the program will be forced to quit, but that's only for safety purposes. The 'exit' feature shouldn't be there in an official interpreter release.