Add a better word-not-found handler

prelude.f

@@ -210,6 +210,30 @@ CHAR . EMIT
 
 CHAR . EMIT
 
+\ A better word-not-found handler
+
+: ANY-RX? RXHEAD AC@ RXTAIL AC@ <> ;
+
+: WNF-HANDLER
+  ." Unknown word: "
+  WORDBUF SWAP TYPE CR
+  STATE @ IF
+	\ Remove incomplete definition and switch back to interpret mode
+	LATEST @ HERE !
+	LATEST @ @ LATEST !
+	[COMPILE] [
+  THEN
+  \ We only consume to the next newline if there is RX data available,
+  \ because if the offending word was at the end of the line then the
+  \ newline would have already been consumed by WORD.
+  ANY-RX? IF BEGIN KEY 10 = UNTIL THEN
+  QUIT
+;
+
+' WNF-HANDLER TO WNFHOOK
+
+CHAR . EMIT
+
 \ Version number
 
 : VERSION-MAJOR 0 ;