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Paradigm(s) imperative
Designed by User:Rphii
Appeared in 2021
Memory system Cell-based
Dimensions one-dimensional
Computational class Unknown
Reference implementation Unimplemented
Influenced by brainfuck
File extension(s) .01

[0,1] or )0,1( is an esoteric programming language created by User:rphii in 2021.


  • Concept of infinity within fixed bounds.
  • brainfuck-ish but different.
  • Interrelation.


There is a theoretical infinitely addressible memory space from index 0 to 1, both 0 and 1 inclusive. Note that in this language it is possible for the index to be any real number, hence the name for this language.


At each memory index there is a variable whose value ranges from 0 to 1, both 0 and 1 inclusive. This also applies to the indexes that access the values (i and j).


For making explanations easier we'll use some abbreviations.

Abbr. Description
i Index 0 (main)
j Index 1 (secondary)
q 10^q
jq j multimplied by q
@i or @j Value at i or at j within memory

j, q & jq

Below we take a closer look at j, q and jq.

j q jq
1 0 1*10^0 = 1*1 = 1
1 1 1*10^1 = 1*10 = 10
1 2 1*10^2 = 1*100 = 100
1 -1 1*10^(-1) = 1*0.1 = 0.1



Command Description
+ Increment q
- Decrement q
^ Flip rotation
~ Swap i and j
= Apply rotation @i with magnitude @j
' Set i to @j
" Set @j to i
* Apply rotation on i with magnitude of jq
[ If no overflow/underflow occured on last rotation jump past matching ]
] If overflow/underflow occured on last rotation jump back to matching [
. Output character of the rounded reciprocal @i
, Input character and store reciprocal value @i

Command: .

Say that we have a value of 0.0139 stored @i. The . command first creates the reciprocal value of @i, in this case 1/0.0139 = 71.9424. This value then gets rounded to 72 and printed as a character, which, according to an ASCII table, corresponds to an H.

Command: ,

Say that the user enters an H. The , command first creates the reciprocal of the ASCII value, in this case 1/72 = 0.013888... and stores it @i

Command: ^

With 'changing rotation' is meant either adding or subtracting. When a program starts, it is initially set to addition. Once that command is executed, rotations get set to subtract mode, until that command changes it back to addition mode.

Illegal operations

If any of the following illegal operations is triggered, the program should stop or else the universe will explode into countless pieces. Stop exploding universes, that's not cool.

  • Be careful with outputting a 0 or you'll maybe anger some mathematicians... Just kidding. It is not allowed to (input nor) output a 0 (note that Ascii 0 with the value 48 can be printed, just not plain old 0).


It is mandatory that each language specifies if initialization takes effect and how. In [0,1] everything is defined by the table below.

Variable Initialized Value
i 0
j 1
q 0
@i i (each memory index initializes its own memory index as a value)


Variable Number set Range
i real numbers 0...1
j real numbers 0...1
q whole numbers -∞...∞
@i real numbers 0...1

Overflowing / Underflowing

  • The = command rotates @i with magnitude @j. (Simply put it adds a value onto another value, but this way it may be easier to imagine)
  • The * command can also rotate numbers.
  • The specification within limits tells us that any number should not be smaller than 0 nor larger than 1.

Conclusion: A number could overflow or underflow. If this happens, a number whould be A) larger than one or B) smaller than 0.

  • In the case of A) the number automatically gets 1 subtracted until it is smaller than or equal to 1.
  • In the case of B) the number automatically gets 1 added, until it is greater than or equal to 0.

The overflow information is stored until another number is rotated.


[0,1] is similarly executed like brainfuck, character for character. Any non-command character is simply ignored.


Truth machine