DRUN

DRUN is a toy programming language designed during first langjam of 2021. The theme of jam is first class comments. Currently in very WIP state so be aware ;) The future updates will be pushed to this repo DRUN GH-REPO

DRUN implements this idea in a way that comments are:

• describing and affecting runtime
• describing and affecting behaviour of code
• code can reach into comments and change its behaviour based on that

For example here is code that can access it's own comment and comment of functions that called it to check if author is kfirmanty and based on that execute code differently

#author kfirmanty
FN ADD(a,b)
 IF ALL_COMMENTS(\"AUTHOR\") CONTAINS \"kfirmanty\" RETURN NIL END
 RETURN a + b
END

Here something similar is implemented purely in the comments. If SUB is called by any code which is authored by kfirmanty it will immediately return value of 5. The comment can contain any valid DRUN code

#if called from code by kfirmanty: RETURN 5 END
#execute 5 to 10 times
FN SUB(a,b)
  RETURN a - b
END

Here another change of behaviour is introduced - if branches can be reversed in order based on comment which can results in interesting behaviour ;)

#if calls have 40% possibility of being reversed in this function and descendants
FN ADD_IF_SMALL(a,b)
 IF a > 2 
  RETURN 2 + b
 ELSE
  RETURN a + b
 END
END

Even more for example all variables can be defined as immutable by comment:

#all variables are immutable
FN ADD_2(a)
  a = a + 2
  RETURN a
END

^ in that case the result will still be original value passed to a. All operations that would breake immutability would be ignored.

It should also be possible to set comments using env variables. For example setting DRUN_MATH_ADD_2=all variables are mutable would override previous comment and variables would be mutable again. Also using ${} syntax comments could access env variables.

#if author is ${SOME_AUTHOR}: RETURN NIL END

How to run it

As of the end of the jam there is not much to run. If you are very inclined then in langjam.vm ns there is test-parse fn where you can replace test code with yours and execute it which should parse the code and execute MAIN fn.