Hi, Ivan Perez wrote:
The function \x -> (x,x) is very convenient when working with arrows. Would it be appropriate to add it to Data.Tuple?
David Feuer replied:
I'm not opposed. Should this be called dup or diagonal? What about larger tuples?
Dan Burton replied:
There is precedent in the arrow literature for calling this function "dup"
It would indeed be unfortunate if it was not called "dup". One could argue, as David (I'm guessing) does, that it's a bit of an odd definition to add to Data.Tuple as it only works for pairs (as implied by its name). And the reason it's convenient for Arrows is that (standard) Arrows are defined in a way that relies on pairs. So maybe it should somehow be defined in relation with Arrows. But then again, all other functions in Data.Tuple are at present specific to pairs ("fst", "snd", "swap", ...). So "dup" would certainly not look out of place there. Best, /Henrik This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.