[Haskell-cafe] Please add a method for optimized concat to the Semigroup class

Stephen Tetley stephen.tetley at gmail.com
Tue May 3 14:03:46 CEST 2011

There is that formulation, though usually I find I need to do it with
an alternative instead:

altconcat alt []     = alt
altconcat _   (a:as) = go a as
    go acc [] = acc
    go acc (b:bs) = go (acc <> b) bs

Both are "kind of, sort of" bringing you up to a Monoid though...

On 3 May 2011 12:56, Holger Siegel <holgersiegel74 at yahoo.de> wrote:

> You have to provide the "neutral" element by yourself:

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