document FatRat

lib/FatRat.pod

@@ -0,0 +1,20 @@
+=begin pod
+
+=TITLE class FatRat
+
+    class FatRat is Cool does Rational[Int, Int]
+
+A C<FatRat> is a rational number stored with arbitrary size numerator and
+denominator. Arithmetic operations involving a C<FatRat> and optionally L<Int>
+or L<Rat> objects return a C<FatRat>, avoiding loss of precision.
+
+Since, unlike L<Rat>, FatRat arithmetics do not fall back L<Num> at some
+point, there is a risk that repeated arithmetic operations generate
+pathologically large numerators and denominators.
+
+There are two common ways to generate C<FatRat> objects: through the
+C<FatRat.new(Int, Int)> constructor, which generates them from numerator and
+denominator, or by calling the C<.FatRat> method on an L<Int> or L<Rat>
+object.
+
+=end pod