Re: [Haskell-cafe] instance Monoid a => Monad ((,) a)

Am 03.08.19 um 01:48 schrieb Neil Mayhew:

On 2019-08-02 5:38 p.m., Benjamin Franksen wrote:

But I could not find the

|instance Monoid a => Monad ((,) a)|

documented anywhere in the base package.

If you look at the list of instances under the definition of |Monad|, you’ll see |Monoid a => Monad ((,) a)| | /Since: 4.9.0.0/ in the list. Clicking on the |# Source| link takes you to the source of |GHC.Base|:

|instance Monoid a => Monad ((,) a) where (u, a) >>= k = case k a of (v, b) -> (u <> v, b) |

Thanks! No idea how/why I missed that. I have stared at that list for quite some time before sending my question, just couldn' see it... And yes, this is exactly the instance I had in mind (with Any instead of Bool). Cheers Ben