Harp (Archived)

This article is not detailed enough and needs to be expanded. Please help us by adding some more information.

Harp is an esoteric programming language.

Structure

Harp is a language with one instruction. Every Harp program asks for an input at the beginning. Every instruction from then on has two parameters, A and B, and does this:

• If last input is equal to A, or A is the empty string

• Ask for input
• Go to B

• Otherwise

• Execute the next instruction

Interpreter

-- split a string into a table by a delimiter
function split(inputstr, sep)
        local t = {}
		local i = 1
		for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
			if str and t and i then
				t[i] = str
				i = i + 1
			end
		end
        return t
end

-- see if the file exists
function file_exists(file)
  local f = io.open(file, "rb")
  if f then f:close() end
  return f ~= nil
end

-- get all lines from a file
function lines_from(file)
  if not file_exists(file) then return {} end
  lines = {}
  for line in io.lines(file) do
    lines[#lines + 1] = line
  end
  return lines
end

function ask()
	return io.read()
end

print("Type in the name of a file.")
local code = lines_from(ask())

local words = {}

for i,j in pairs(code) do
	words[i] = split(j, " ")
end

local input = ask()

local i = 1
while i <= #code do
	if input == "exit" then
		print("DEBUG:", "quitting...")
		return
	end
	if input == words[i][1] or words[i][1] == "" then
		print("DEBUG:", "goto", words[i][2])
		input = ask()
		i = tonumber(words[i][2]) - 1
	elseif not words[i][2] then
		print("DEBUG:", "goto", words[i][1])
		input = ask()
		i = tonumber(words[i][1]) - 1
	end
	i = i + 1
end