CAOS language spec

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This describes the known CAOS language as used in the Creatures Evolution Engine.

basic token types

These are the types of tokens which can be present in CAOS source files.

  • integer - any signed 32-bit integer, literals are capped at the limits not overflowed
    • literals can be in binary, eg %010101
    • literals can be characters, eg 'A' or '$'
      • don't think you can have a ' as a char - escaping doesn't work
  • float - any float (?)
  • string - any string, enclosed in double-quotes, \", \\ and \n are valid (more?)
  • bytestring - a bunch of bytes enclosed in square brackets, eg [1 2 15 255]
    • you can use any integer as the values (so binary/characters are valid)
  • function - four-character identifier representing a CAOS function
  • label - as used by GSUB, GOTO and SUBR

additional parameter types

These are types which aren't in the above list but can be used as parameters or return values.

  • anything - like it says, any type.
  • decimal - either an integer or a float
    • note that CAOS will cast integers to floats and vice versa when passing parameters. casting float to integer rounds.
    • so decimal is only used when type needs preserving, eg for OUTV
  • variable - a variable (ie, the result of VAxx/OVxx/etc)
  • agent - an agent.


Tokens are normally separated by whitespace of some kind. Newlines are just treated as normal whitespace.

  • commands can span several lines
  • there can be several on a line.

However, there is no need for whitespace directly after a string, bytestring or decimal.

  • This may be a bug in CEE. It's present in openc2e too for compatibility reasons.

CAOS source files are made up of CAOS commands (functions without a return value), one after another.

  • eg: 'OUTV 1 OUTV %01011 OUTS "hello"'

Obviously you can use functions too.

    • note it's impossible to work out when functions/commands start/end if you don't know their details
    • this is why it's good for coders to keep one-command-per-line, although this isn't helpful *enough*


Conditions compare variables/literals. For instance, 'VA00 > 4'.

Condition operators: <> = >= > <= <

Text equivalents (can be used interchangably): NE EQ GE GT LE LT

  • so 'VA00 GT 4' is equivalent to the above example.

You can join conditions together with 'AND' or 'OR'.

  • eg: 'VA00 > 4 OR VA01 EQ 2'.

They're evaluated simply from left to right.

  • 'a OR b AND c' means '(a OR b) AND c', not 'a OR (b AND c)'.
    • you're stuck with this, brackets aren't allowed.
  • this means you can step along one-at-a-time and just combine with the last result based on whether it was joined by an AND or OR.
  • conditions do not short-circuit

When comparing integer and float, the integer is cast to float first (3.6 eq 4 is not true, but 4.0 eq 4 is).

Used with: DOIF, ELIF, UNTL.

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