fjwhittle / Update ch-1 to use iterators, more elegant loop

1 files changed, 10 insertions, 20 deletions

diff --git a/challenge-003/fjwhittle/perl6/ch-1.p6 b/challenge-003/fjwhittle/perl6/ch-1.p6
index 25785ed2e2..0232dfceba 100644
--- a/challenge-003/fjwhittle/perl6/ch-1.p6
+++ b/challenge-003/fjwhittle/perl6/ch-1.p6
@@ -11,34 +11,24 @@ unit sub MAIN(
 );
 
 # Use a lazy list to generate 5-smooth numbers
-my @smooth5 = lazy gather {
-  take 1; # 1 is the first
-
-  # Initialize some iteration counters.
-  my ($i2, $i3, $i5) = 0 xx 3;
-
-  # I wanted to use actualy Iterators here, but couldn't figure out how to not
-  # pull elements that didn't exist yet.
-
-  # Generate the next number for each divisor
-  my $n2 = @smooth5[$i2++] * 2;
-  my $n3 = @smooth5[$i3++] * 3;
-  my $n5 = @smooth5[$i5++] * 5;
+my $smooth5 = gather {
+  # Initialize some iterators.
+  my ($i2, $i3, $i5) := ($smooth5.iterator for ^3);
+  my ($n2, $n3, $n5) := 1 xx 3;
 
   # Just keep generating.  Does the list become sparse?  I don't know!
   loop {
     # Minimum of the latest iterations
-    my $n = ($n2, $n3, $n5).min;
-    take $n;
+    take my $n := ($n2, $n3, $n5).min;
 
-    # Advance the generators that matched.
-    $n2 == $n and $n2 = @smooth5[$i2++] * 2;
-    $n3 == $n and $n3 = @smooth5[$i3++] * 3;
-    $n5 == $n and $n5 = @smooth5[$i5++] * 5;
+    # Advance the iterators that matched.
+    $n2 == $n and $n2 := $i2.pull-one * 2;
+    $n3 == $n and $n3 := $i3.pull-one * 3;
+    $n5 == $n and $n5 := $i5.pull-one * 5;
   }
 }
 
-@smooth5.[^$count].say;
+$smooth5.[^$count].say;
 
 for @print -> $n {
   ($n.fmt('%7d') ~ ': ' ~ @smooth5[$n-1]).say;