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repeatfactor-lang

Is it possible to create a repeat function in Factor Code?

I'm trying to create a function in Factor Code called repeat which expects a non-negative integer n and quotation q following it. It causes q and n to be popped off the stack and then the contents of q executed n times.

So the if the code 

[drop] 5 repeat

was executed it would apply drop to the top of the stack 5 times.

I was wondering is it possible to write this in Factor Code or will I have to edit the interpreter and add repeat as a new function that way?

Solution

  • Using recursion:

    : repeat ( quot n -- ) dup 0 > [ over 2dip 1 - repeat ] [ 2drop ] if ; inline

    Using a loop:

    : repeat ( quot n -- ) [ dup 0 > ] [ over 2dip 1 - ] while 2drop ; inline

    Finally, using a pre-defined vocabulary word times:

    : repeat ( quot n -- ) swap times ; inline