FEAT: implemented ask/char, which waits only for a single key press

Author: Oldes

src/mezz/mezz-files.reb

@@ -104,9 +104,10 @@ ask: func [
 	question [series!] "Prompt to user"
 	/hide "Turns off echoing inputs"
 	/char "Waits only on single key press and returns char as a result"
+	 limit [bitset! string! block! char! none!] "Limit input to specified chars or control words"
 ][
 	prin question
-	input/:hide
+	either char [wait-for-key/only limit][input/:hide]
 ]
 
 confirm: func [

src/mezz/mezz-shell.reb

@@ -131,7 +131,7 @@ file-checksum: function [
 
 wait-for-key: func[
 	"Wait for single key press and return char (or word for control keys) as a result"
-	/only limit [bitset! string! block!] "Limit input to specified chars or control words"
+	/only limit [bitset! string! block! none! char!] "Limit input to specified chars or control words"
 	/local port old-awake
 ][
 	;; using existing input port
@@ -153,6 +153,8 @@ wait-for-key: func[
 			true
 		]
 	]
+	;; handle single char limit
+	if char? limit [limit: to string! limit]
 	;; wait for user input
 	wait/only port
 	;; put back original awake actor and read-line mode