[commit: nofib] master: Result class: Provide a way to sum results (7d9617d)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/nofib

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/7d9617d20e4de27ce8619b2039f5381e394eef03/nofib

>---------------------------------------------------------------

commit 7d9617d20e4de27ce8619b2039f5381e394eef03
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Fri Oct 23 11:11:08 2015 +0200

    Result class: Provide a way to sum results


>---------------------------------------------------------------

7d9617d20e4de27ce8619b2039f5381e394eef03
 nofib-analyse/Main.hs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/nofib-analyse/Main.hs b/nofib-analyse/Main.hs
index daba809..6200a77 100644
--- a/nofib-analyse/Main.hs
+++ b/nofib-analyse/Main.hs
@@ -734,6 +734,7 @@ class Result a where
    toBox    :: a -> BoxValue
    float    :: a -> Float
    variance :: a -> Float
+   sumResult :: [a] -> a
 
 -- We assume an Int is a size, and print it in kilobytes.
 
@@ -741,6 +742,7 @@ instance Result Int where
     toBox  = BoxInt
     float a = fromIntegral a
     variance a = 0
+    sumResult = sum
 
 data MeanStdDev a = MeanStdDev a Float
 
@@ -748,16 +750,24 @@ instance Result a => Result (MeanStdDev a) where
     toBox    (MeanStdDev a b) = BoxStdDev (toBox a) b
     float    (MeanStdDev a _) = float a
     variance (MeanStdDev _ b) = b
+    -- This summing of standard deviations is only valid if the
+    -- random variables are indepenent. If we assume that variance in measurements
+    -- is random noise, then this should be ok
+    sumResult mss = MeanStdDev
+        (sumResult [m | MeanStdDev m _ <- mss])
+        (sqrt $ sum [s^2 | MeanStdDev _ s <- mss])
 
 instance Result Integer where
     toBox = BoxInteger
     float a = fromIntegral a
     variance a = 0
+    sumResult = sum
 
 instance Result Float where
     toBox = BoxFloat
     float a = realToFrac a
     variance a = 0
+    sumResult = sum
 
 -- -----------------------------------------------------------------------------
 -- BoxValues