yet another approach

more.rx

( useful things )
: dictionary.find/xt ( string:name - xt )  find [ @d->xt ] [ drop #0 ] if ;
: getc:internal  ( -c )  &getc 2 + @ do ;

( keymap )
9 variable: prefix:CHAR
create prefix:TABLE  256 allot

( We will lookup the keymap by name, to allow for per-application maps )

[ dup @prefix:CHAR ==
  [ drop getc:internal
    "prefix:TABLE" dictionary.find/xt + @ dup 0 <>
    [ dip cr ] [ drop ] if 0
  ] ifTrue
  dup '| ==
  [ drop getc:internal dup putc space "prefix:TABLE" dictionary.find/xt + &' do swap ! cr 0 ] ifTrue
] is remapKeys

: prefix:tab   09 !prefix:CHAR ;
: prefix:space 32 !prefix:CHAR ;

: (matching) ;
: bindTo: ( quote "character" - )
  getc "prefix:TABLE" dictionary.find/xt + ! ;

[ cr
  "?        help text\n" puts
  "d<word>  documentation for word\n" puts
  "s        show stack contents\n" puts
  "p<char>  change trigger character to <char>\n" puts ] bindTo: ?

[ "display docs for: " puts
  getToken find [ cr @d->doc 0; puts ] [ drop cr "no docs found!" puts ] if ] bindTo: d

[ "display functions matching: " puts
  getToken cr (matching) ] bindTo: m

[ getc:internal dup putc !prefix:CHAR ] bindTo: p

|wwords
|s.s