My BASIC is almost working, the almost being the
DEF FN. Just so I don't paint myself into a corner, is there any "mainstream" BASIC from the 8-bit era that allowed user-defined string functions?
I'm mainly using "The Basic Language" from BASIC Computer Games as my guide to the language, and it doesn't really say much on the topic. All use of
DEF in the book is always math. Commodore BASICs definitely don't support string functions, the right-hand-side must be a mathematical expression, and I suspect this is true for most others derived from it.
Are there any major 8-bit dialects that supported this - TRS-80, Coco, TI-99, Sinclair, BBC, etc? Not trying to do GW or even MSX, but I would be curious to know if they did.