instance Applicative Data.Map

Tyson Whitehead twhitehead at
Wed Nov 14 23:22:52 CET 2012

On November 14, 2012 15:28:06 Henning Thielemann wrote:
> Yes, that would work. It is only annoying that for liftA3 I do not need
> 'pure', at all. Thus we may note in the record that Data.Map is an example
> where <*> and liftAn make sense (for n>0) but 'pure' (i.e. Pointed) cannot
> be defined.

Sorry for jumping in in the middle without have really followed the 
conversation, but, assuming you want to define (<*>) without pure, would you 
also happen to want to define join without return?

That is, is it also sensibly a non-Pointed Monad?

Cheers!  -Tyson

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