Simplify example

Per https://colabti.org/irclogger/irclogger_log/perl6-dev?date=2018-10-30#l379

Author: zoffixznet

doc/Language/grammars.pod6

@@ -274,9 +274,9 @@ succeed assertion.
 
 In the action class, we use calls to the C<succ> method to do set up (in this
 case, we prepare a new element in C<@!numbers>). In the C<digit> method,
-we convert an Arabic digit into a Devanagari digit and add it to the last
-element of C<@!numbers>. Thanks to C<succ>, the last element will always be
-the number for the currently parsed C<digit> digits.
+we use the Arabic digit as an index into a list of Devanagari digits and add
+it to the last element of C<@!numbers>. Thanks to C<succ>, the last element
+will always be the number for the currently parsed C<digit> digits.
 
     grammar Digifier {
         rule TOP {
@@ -288,7 +288,7 @@ the number for the currently parsed C<digit> digits.
 
     class Devanagari {
         has @!numbers;
-        method digit ($/) { @!numbers[*-1] ~= $/.ord.&[+](2358).chr }
+        method digit ($/) { @!numbers.tail ~= <०  १  २  ३  ४  ५  ६  ७  ८  ९>[$/] }
         method succ  ($)  { @!numbers.push: ''     }
         method TOP   ($/) { make @!numbers[^(*-1)] }
     }