Christopher


        // Welcome to Christopher!
        //
        // Christopher is a Turing machine
        // simulator. You program it with a
        // language designed specifically
        // for it called Tlang. Here's an
        // example program that increments
        // in binary:
        main | * | R -> move
        move | 1 | R -> move
        move | 0 | R -> move
        move | | L -> flip
        flip | 0 | P(1) R -> move
        flip | 1 | P(0) L -> flip
        flip | | P(1) R -> move

        // All programs start in state "main".
        // You have access to 4 instructions:
        //
        // - R moves the tape head right
        // - L moves the tape head left
        // - P(x) prints x to the tape
        // - H halts the machine
        //
        // Then -> moves to the next state.
        // If no -> is found on a line, it
        // is assumed you wish to halt.
        // If you're not familiar with Turing
        // machines, I recommend you read the
        // article I wrote about them:
        // https://samwho.dev/turing-machines
        //
        // I use this simulator heavily in the
        // article, and anything it can do there
        // you can do here.
        //
        // I love to hear from folks who have
        // used my work in their own projects or
        // education. If this is you, please
        // reach out and say hi! My email is
        // hello@samwho.dev.
        //
        // Have fun!


        main | * | P(1) R P(1) R P(0) R R P(0) R P(1) R P(1) L L L L L L -> b1

        b1 | 0 | R -> b1
        b1 | 1 | R -> b1
        b1 |   | R -> b2

        b2 | 0 | R -> b2
        b2 | 1 | R -> b2
        b2 |   | L -> dec

        dec | 0 | P(1) L -> dec
        dec | 1 | P(0) L -> b3
        dec |   | H

        b3 | 0 | L -> b3
        b3 | 1 | L -> b3
        b3 |   | L -> inc

        inc | 0 | P(1) R -> b1
        inc | 1 | P(0) L -> inc
        inc |   | P(1) R -> b1


        main | * | R -> move

        move | 1 | R -> move
        move | 0 | R -> move
        move |   | L -> flip
        flip | 0 | P(1) R -> move
        flip | 1 | P(0) L -> flip
        flip |   | P(1) R -> move


        main | * | R -> inc

        inc    | 0 | P(1)   -> back
        inc    | 1 | P(2)   -> back
        inc    | 2 | P(3)   -> back
        inc    | 3 | P(4)   -> back
        inc    | 4 | P(5)   -> back
        inc    | 5 | P(6)   -> back
        inc    | 6 | P(7)   -> back
        inc    | 7 | P(8)   -> back
        inc    | 8 | P(9)   -> back
        inc    | 9 | P(0) L -> inc
        inc    |   | P(1)   -> back
        back   |   | L -> inc
        back   | * | R -> back


        main  | * | R R P(0) R P(1) R P(0) R -> initb
        initb | * | R P(0) R P(1) R P(1) R -> start

        start | * | L -> start
        start | H | R -> go_a

        go_a | * | R -> go_a
        go_a | A | R R R -> dec_a

        dec_a  | 0 | P(1) L -> cry_a
        dec_a  | 1 | P(0) -> go_c1

        cry_a | 0 | P(1) L -> cry_a
        cry_a | 1 | P(0) -> go_c1
        cry_a | * | R P(0) R P(0) R P(0) -> goto_b

        go_c1 | * | R -> go_c1
        go_c1 | C | R R R -> inc_c1

        inc_c1 | 0 | P(1) -> h2a
        inc_c1 | 1 | P(0) L -> cry_ca

        cry_ca | 0 | P(1) -> h2a
        cry_ca | 1 | P(0) L -> cry_ca
        cry_ca | * | R -> h2a

        h2a | * | L -> h2a
        h2a | H | R -> go_a

        goto_b | * | R -> goto_b
        goto_b | B | R R R -> dec_b

        dec_b | 0 | P(1) L -> dec_bc
        dec_b | 1 | P(0) -> go_c2

        dec_bc | 0 | P(1) L -> dec_bc
        dec_bc | 1 | P(0) -> go_c2
        dec_bc | * | R P(0) R P(0) R P(0) -> end

        go_c2 | * | R -> go_c2
        go_c2 | C | R R R -> inc_c2

        inc_c2 | 0 | P(1) -> go_hb
        inc_c2 | 1 | P(0) L -> cry_cb

        cry_cb | 0 | P(1) -> go_hb
        cry_cb | 1 | P(0) L -> cry_cb
        cry_cb | * | R -> go_hb

        go_hb | * | L -> go_hb
        go_hb | H | R -> goto_b

        end | * | L -> end
        end | H | H