retroforth/example/numeric-ranges.retro

This implements some words to return a range of numbers on the stack.
It's probably best to capture these values in an array.

First is a word to return values from a lower to upper limit, incrementing
upwards. The returned values are inclusive of the limits.

~~~
:range-inc (lh-a)
  over - n:inc [ I over + swap ] indexed-times drop ;
~~~

Next is a word to return values from an upper to lower limit, decrementing
upwards. The returned values are inclusive of the limits.

~~~
:range-dec (hl-a)
  over &- dip swap n:inc [ I over swap - swap ] indexed-times drop ;
~~~

The last word takes the limits and calls the appropriate word.

~~~
:range (nn-a)
  dup-pair gt? [ range-dec ] [ range-inc ] choose ;
~~~

As a simple test case:

```
{ #1 #5 range } [ n:put sp ] a:for-each
```