Classic EForth

EForth is a delightfully minimalist approach to Forth originated by Bill Muench and Dr. C. H. Ting.

Classic ESP32forth

ESP32forth - Version 6.3 for NodeMCU ESP32S - Tweaked for the Web

ESP32forth-6.3.0.ino - This has Dr. Ting's v6.3 version with WebUI added in

Classic EForth Quirks

EForth exclusively uses FOR..NEXT in favor of DO..LOOP. Details

This construct has the odd property that it iterates one "extra" time for zero.

: FOO 10 FOR R@ . NEXT ; FOO
 10 9 8 7 6 5 4 3 2 1 0  ok

To permit a more ordinary loop the AFT word is used in the sequence FOR..AFT..THEN..NEXT.

: FOO 10 FOR ( 1st time only ) AFT R@ . THEN NEXT ; FOO
 9 8 7 6 5 4 3 2 1 0  ok

The even more enigmatic FOR..WHILE..NEXT..ELSE..THEN is used in place of DO..LEAVE..LOOP. It allows a while condition to early out of a counted loop.