Prequel
primitive recursive driven programming


Factorial

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Enter an integer number between 0 and 12.

! = ...

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0
0
0
← calls
← instructions
← memory (max use: 0)


Prequel program

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Module: FACTORIAL

 n := FACTORIAL.INPUT     
 result := 1              
 REPEAT n                 
   result *= n+1          
 ENDREP                   
 FACTORIAL.RETURN(result) 
	

Input:

FACTORIAL.INPUT
  The integer written in the editable text input.
  -> e.g. 5
MODULE.CALL.ARGS
  Holds the list of arguments passed with MODULE.CALL.
  -> [arg1, ..., argN]

Procedures:

FACTORIAL.RETURN(result)
  End computation and show the calculated value.
  -> result: calculated integer value
MODULE.CALL(&retvar1, ..., &retvarM, @modname, arg1, ..., argN)
  Start executing module modname, copying N arguments and expecting M return values.
  -> retvar: name of variable to hold the corresponding return value retval
  -> modname: name of module to start executing
  -> arg: value to be copied to the list MODULE.CALL.ARGS
  Alternative syntax: retvar1, ..., retvarM := MODULE.CALL(@modname, arg1, ..., argN)
  Note that recursive module calls are not allowed.
MODULE.RETURN(retval1, ..., retvalM)
  Return M values from the current module.
  Resume execution at the next instruction of the corresponding MODULE.CALL.
  -> retval: value to be copied to the corresponding variable retvar

Additional examples can be found on GitHub.