add comments

2 files changed, 7 insertions, 7 deletions

diff --git a/challenge-112/feng-chang/raku/ch-1.raku b/challenge-112/feng-chang/raku/ch-1.raku
index 5175350730..cf4cf08e00 100755
--- a/challenge-112/feng-chang/raku/ch-1.raku
+++ b/challenge-112/feng-chang/raku/ch-1.raku
@@ -1,20 +1,20 @@
 #!/bin/env raku
 
 sub MAIN(Str:D $path where * ~~ rx{^'/'}) {
-    my @dirs = $path.split(rx{'/'+}).tail(*-1);
-    @dirs.pop unless @dirs[*-1];
+    my @dirs = $path.split(rx{'/'+}).tail(*-1);     # put all directory names into an array, omit first empty element
+    @dirs.pop unless @dirs[*-1];                    # omit last element if it is empty
     my $i = 0;
     try {
         while $i < @dirs.elems {
             given @dirs[$i] {
-                when '.'  { @dirs.splice($i, 1) }
-                when '..' { @dirs.splice($i-1, 2); --$i; }
+                when '.'  { @dirs.splice($i, 1) }           # omit '.'
+                when '..' { @dirs.splice($i-1, 2); --$i; }  # omit '..' and its upper directory
                 default   { ++$i }
             }
         }
 
         CATCH {
-            $*ERR.put: 'cannot walk beyond root';
+            $*ERR.put: 'cannot walk beyond root';   # guard against excessive '..'s
             exit;
         }
     }
diff --git a/challenge-112/feng-chang/raku/ch-2.raku b/challenge-112/feng-chang/raku/ch-2.raku
index f0ea1a093b..b674d7b518 100755
--- a/challenge-112/feng-chang/raku/ch-2.raku
+++ b/challenge-112/feng-chang/raku/ch-2.raku
@@ -1,13 +1,13 @@
 #!/bin/env raku
 
-proto walk(UInt:D --> UInt:D) {*}
+proto walk(UInt:D --> UInt:D) {*}   # restrict dispatch pattern
 
 multi walk(0)  { 1 }
 multi walk(1)  { 1 }
 multi walk(2)  { 2 }
 
 multi walk($n) {
-    state @memo;
+    state @memo;                    # use memory to speed up counting
     @memo[$n] = walk($n-1) + walk($n-2) unless @memo[$n].defined;
     @memo[$n];
 }