measurable

commit c2cad7d41c1000eb85ae5414dfc46f55dde521aa
parent 5481d0f68053ba386c59244228d69503d85fc3b9
Author: Jared Tobin <jared@jtobin.ca>
Date:   Fri, 18 Oct 2013 11:30:58 +1300

Add applicative instance.

Diffstat:
M
src/Measurable.hs
 | 
10
+++++++---

1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/src/Measurable.hs b/src/Measurable.hs
@@ -48,13 +48,17 @@ import Numeric.Integration.TanhSinh
 
 newtype Measure a = Measure { measure :: (a -> Double) -> Double }
 
-instance Functor Measure where
-  fmap = push
-
 instance Fractional a => Monoid (Measure a) where
   mempty  = identityMeasure
   mappend = convolute
 
+instance Functor Measure where
+  fmap = push
+
+instance Applicative Measure where
+  pure  = return
+  (<*>) = ap
+
 instance Monad Measure where
   return x = Measure (\f -> f x)
   mu >>= f = Measure $ \d ->