Beam

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Beam is yet another two dimensional language thought of around mid-2010 by User:Feuermonster and implemented and published in 2012.

  • The start-up direction is right.
  • There is a beam which holds an 8bit unsigned value.
  • Also there is a store which can hold an arbitrary large positive value. If it drops below zero it's wrapped to 255.
  • Then there is an infinite amount of 8bit memory cells.
  • The implementation uses NUL (\0) if no character could be read from stdin.
  • Every character which is not an instruction is a NOP.

Instructions

 > Set the direction to right
 < Set the direction to left
 ^ Set the direction to up
 v Set the direction to down
 + Increment the beam
 - Decrement the beam
 @ Output the beam as character
 : Output the beam as number
 / Redirect the control flow like this:

       |
   ----/        /---
                |
   (90 degrees to the left)

 \ Redirect the control flow like this:

           |
 -----\    \----
      |

   (90 degrees to the right)

 ! If the beam is not 0, reverse the control flow. (It bounces off the !)
 ? If the beam is 0, reverse the control flow. (It bounces off the ?)
 | Reverse the control flow if coming from a right/left-direction
 _ Reverse the control flow if coming from a up/down-direction
 H stop the program
 S store = beam
 L beam = store
 s memory[beam] = store
 g store = memory[beam]
 P memory[store] = beam
 p beam = memory[store]
 u If beam != store change direction to up
 n if beam != store change direction to down
 ` Decrement the store
 ' Increment the store
 ) If store != 0 change direction to left
 ( If store != 0 change direction to right
 r Read character from input

It should be noted, that 'u' and 'n' perform 32bit comparison: if the store exceeds 255 the comparison beam != store is always true since beam can not exceed 255. Lines are not padded to equal length. A compliant interpreter is not allowed to do this!

Example programs

Reverse stdin


'>   rP   n
 ^!p'<vn(`<
     ^ <
      >'p!`>`p@ v
            Hnp`<
           ^ <

Painfully written by hand.

A faster version (thanks to User:Fizzie):


>'p!rP(`)n>'p!`v
^        <    H(`p@p`)H
               H

Fastest version in the west (also thanks to User:Fizzie):


v
(>``v
!  H(p`@`p)H
P   H
' 
r 
' 
P 
! 
>^

Truth-machine

rS v
>@<)
   @

(Expects NUL or SOH from stdin.)

Hello

Prints Hello!

'''''v
     >`++++++++++++++)++@v
v++++++@-(++++++++++`<'''<
>+@@+++@>-!'''>`++++++++++)v
                       @+++<

Even / Odd

Reads from stdin and tests if the value (ascii value) is even or odd. If it is even, it prints a zero, else a one.

rv`<
  :u'<
 >-- u:

Cat

>r@nH
^  <

Compare

Reads in two ascii characters and prints out the smaller one.

rP'Pr'P'P```v     <
           H @p'''u``p''<
            >p-P''p-P``pu'p@

Turing completeness

Brainfuck programs can be translated to Beam programs. This mechanism works with the 'u' instruction and marking cells to restore the store.

Brainfuck

,[>+>+<<-]++++++[>--------<-]>[>.<]>.

Beam (translation with the bf2beam perl script)

v               > v                                             > v                                       > v
>'''rP>`p+P'p(`)uv>'>'p?-P'''p+P''p+P````p-Pv>p++++++P>`p+P'p(`)uv>'>'p?-P'''p--------P``p-Pv>''>`p+P'p(`)uv>'>'p?-P'''p@``v>''p@H
                 > '>'p?-P'                  ^                   > '>'p?-P'                  ^             > '>'p?-P'       ^     
      ^                                     <         ^                                     <   ^                          <       

Beam constants

Constants to set the beam to a specific value (requires store to be zero.). This list is not complete. Help me!

Number Code Bytes Cycles Cycles / Bytes Cycles / Number
24 '''>`++++++++) 14 34 2.42 1.42
24 '''''>`+++++)- 14 42 3 1.75
25 '''''>`+++++) 13 41 3.15 1.64
25 '''>`++++++++)+ 15 35 2.33 1.39
26 '''''>`+++++)+ 14 42 3 1.61
26 '''>`+++++++++)- 16 38 2.38 1.46
27 '''>`+++++++++) 15 37 2.46 1.37
28 '''''''>`++++) 14 50 3.57 1.78
28 '''>`+++++++++)+ 16 38 2.38 1.36
28 '''''>`++++++)-- 16 48 3 1.71

Implementation

Work in progress

  • Finding Beam constants.
  • Describing some techniques to program in Beam.
  • WeBeam (to program webpages).

Help is always welcome.

External resources