In Gforth 1.0 you can use the return stack during text interpretation.
The only limitation here is that you cannot pass data on the return
stack into or out of an included file, block, or evaluated
string. This interpretive usage of return-stack words is
non-standard, and many other Forth systems do not have support this
usage, or limit it to within one line. Example:
1 >r : foo [ r> ] literal ; foo . \ prints 1
In Gforth you can use the return stack for storing data while you also keep and access data in locals. However, the standard puts restrictions on mixing return stack and locals usage, for easy locals implementations, and there are systems that actually rely on these restrictions. So, if you want to produce a standard compliant program and you are using local variables in a definition, forget about return stack manipulations in that word (refer to the standard document for the exact rules).
>r ( w – R:w ) core “to-r”
r> ( R:w – w ) core “r-from”
r@ ( R:w – R:w w ) core “r-fetch”
r'@ ( r:w r:w2 – r:w r:w2 w ) gforth-1.0 “r-tick-fetch”
The second item on the return stack
rpick ( R:wu ... R:w0 u – R:wu ... R:w0 wu ) gforth-1.0 “rpick”
wu is the uth element on the return stack; 0
rpick is equivalent to r@.
rdrop ( R:w – ) gforth-0.2 “rdrop”
2>r ( w1 w2 – R:w1 R:w2 ) core-ext “two-to-r”
2r> ( R:w1 R:w2 – w1 w2 ) core-ext “two-r-from”
2r@ ( R:w1 R:w2 – R:w1 R:w2 w1 w2 ) core-ext “two-r-fetch”
2rdrop ( R:w1 R:w2 – ) gforth-0.2 “two-r-drop”
n>r ( x1 .. xn n – R:xn..R:x1 R:n ) tools-ext “n-to-r”
nr> ( R:xn..R:x1 R:n – x1 .. xn n ) tools-ext “n-r-from”