do  -- Simple BF interpreter, based on the Lua sample: "Simple meta-implementation using load"
    --                        reads the BF code from stdin, builds an equivalent Pluto program and executes it

    local bfOp <const> = { ['>'] = 'ptr += 1 '
                         , ['<'] = 'ptr -= 1 '
                         , ['+'] = 'mem[ptr] += 1 '
                         , ['-'] = 'mem[ptr] -= 1 '
                         , ['['] = 'while mem[ptr] != 0 do '
                         , [']'] = 'end '
                         , ['.'] = 'io.write(string.char(mem[ptr])) '
                         , [','] = 'mem[ptr] = string.byte(io.read(1) ?? "\\0") '
                         };

    local bfProgram = "local mem = setmetatable({}, { __index = function() return 0 end })\n"
                   .. "local ptr = 1\n"

    for line in io.lines() do
        for p = 1, # line do
            local snippet = bfOp[ line[ p ] ]
            if snippet then bfProgram ..= snippet .. "\n" end
        end
    end

    local bfCode, msg = load( bfProgram )
    if bfCode then bfCode() else error( msg ) end

end