First-draft implementation of Rat datatype.

src/setting/Rat.pm

@@ -0,0 +1,47 @@
+class Rat {
+    has $.numerator;
+    has $.denominator;
+
+    multi method new(Int $numerator is copy, Int $denominator is copy) {
+        if $denominator < 0 {
+            $numerator = -$numerator;
+            $denominator = -$denominator;
+        }
+        self.bless(*, :$numerator, :$denominator);
+    }
+
+    multi method Str() { "$!numerator/$!denominator"; }
+
+    multi method Num() { $!numerator + 0.0 / $!denominator }
+}
+
+multi sub infix:<+>(Rat $a, Rat $b) {
+    Rat.new($a.numerator * $b.denominator + $b.numerator * $a.denominator,
+            $a.denominator * $b.denominator );
+}
+
+multi sub infix:<+>(Rat $a, Int $b) {
+    Rat.new($a.numerator + $b * $a.denominator, $a.denominator);
+}
+
+multi sub infix:<+>(Int $a, Rat $b) {
+    Rat.new($a * $b.denominator + $b.numerator, $b.denominator);
+}
+
+multi sub infix:<->(Rat $a, Rat $b) {
+    Rat.new($a.numerator * $b.denominator + $b.numerator * $a.denominator,
+            $a.denominator * $b.denominator );
+}
+
+multi sub infix:<->(Rat $a, Int $b) {
+    Rat.new($a.numerator - $b * $a.denominator, $a.denominator);
+}
+
+multi sub infix:<*>(Rat $a, Rat $b) {
+    Rat.new($a.numerator * $b.numerator, $a.denominator * $b.denominator);
+}
+
+multi sub infix:</>(Rat $a, Rat $b) {
+    Rat.new($a.numerator * $b.denominator, $a.denominator * $b.numerator);
+}
+