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Today's Topics:
1. Function to compute the mean (Joe King)
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Message: 1
Date: Sat, 8 May 2021 09:39:50 +0000 (UTC)
From: Joe King <joeking1...@yahoo.com>
To: "beginners@haskell.org" <beginners@haskell.org>
Subject: [Haskell-beginners] Function to compute the mean
Message-ID: <1095405637.961440.1620466790...@mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Greeetings I am new here and pretty new to Haskell.
I was wondering what are the relative advanatges/disadvatnages of specifying a
mean function in these two ways:
mean :: [Double] -> Double
mean xs = sum xs / fromIntegral (length xs)
and
mean1 :: (Real a, Fractional b) => [a] -> b
mean1 xs = realToFrac (sum xs) / genericLength xs
I understand that mean1 has the advantage that it can be called with lists of
any Real type, so would work with things like
foo :: [Int]
foo = [1,2,3]
mean foo
-- type mismatch error
mean1 foo
-- no error
But suppose that I know I will only ever use lists of Double, is there still
any advantage (or disadvantage of using mean1). For example is there any
performance benefit by using mean in that case since mean1 has additional
function evaluation.
Are there any other considerations ?
Thanks in advance
JK
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