Hi, On 02/18/2016 12:41 PM, Manuel Gómez wrote:
And whenever I have wanted to map on tuple fields (which I do from time to time), I most certainly want the ability to map on any field. Anyone with a couple of decades of Haskell experience ought to understand that the desire to map on any field of a record cannot be served by a typeclass such as Functor.
Yes, that's exactly my point: functor is not the right tool. So why make tuples instances of functor in the first place? And yes, there is arguably an asymmetry of sorts in having to pick an order among type constructor arguments. But that does not change the fact that there is symmetry in having a projection function for each field. So why even entertain a notion of mapping that doesn't grant the same privileges to all fields? Might be useful in some specialist applications, but certainly not what I, at least, would consider particularly useful. Best, /Henrik -- Henrik Nilsson School of Computer Science The University of Nottingham nhn@cs.nott.ac.uk 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 send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system, you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.