>As I understand it, the FOR loop's TO range is evaluated at the start of the expression, and then not re-evaluated. Is there any way to make it be re-evaluated (a SYS() function or other setting)? Or do I need to switch to a DO WHILE loop and manually increment my loop variable?
>
>

LOCAL lnI
>CLEAR
>
>? "FOR loop:"
>lnI = 0
>FOR lnI = 1 TO test(lnI)
>    ? lnI
>NEXT
>
>? ""
>? "DO loop:"
>lnI = 1
>DO WHILE lnI < test(lnI)
>    ? lnI
>    lnI = lnI + 1
>    IF lnI >= 5
>        EXIT
>    ENDIF
>ENDDO
>
>FUNCTION test
>LPARAMETERS tnI
>    RETURN tnI + 1
>

I'd suggest using a DO WHILE loop as changing the loop boundaries in a FOR loop is usually considered bad form in most languages. In some languages the definition may state that doing so is considered an error -- but leaves it to the implementation on what actually happens (i.e. it may give runtime error, or it might not).