I would like to thank Owen Stephens, Alexander Batischev, Denis Kasak and Mann mit Hut for the valuable comments! I am going to update the tutorial to fix the indicated issues. Also, I am going to improve description of kinds and singletons. Also, I will improve description of red-black tree example: I think I need to include the whole listing after every big step.
Are there any other topics you would like to be described in the context of a practical-oriented introductory-level tutorial on GADTs? PS: Please let me know if I misspelled your names (to make sure that I do not put wrong names in acknowledgements section). You can do it by email to anton dot dergunov dog mail dot ru. -- Best Regards, Anton Dergunov Среда, 9 января 2013, 17:13 +02:00 от Alexander Batischev <[email protected]>: >On Tue, Jan 08, 2013 at 11:22:39PM +0400, Anton Dergunov wrote: >> I have written a draft of an introductory-level tutorial paper about >> GADTs in Haskell (for submittion to proceedings of the recent LASER >> summer school) and I would like to seek initial feedback about its >> content: what information is probably missing? are there any subtle >> mistakes? > >Not exactly the feedback you asked for, but I hope it still can be of >some use. > >As a person with no prior knowledge about GADTs, I found your paper a >good introduction. Following proof of correctness of red-black tree >insertions turned out to be a little bit of a challenge as type >annotations quickly become tangled (made me wondering how one should >prove correctness of the proof). > >I particularly liked how you handle things that are not central to >tutorial, like phantom and existential types: you give single-sentence >explanation that provides good enough intuition to follow you further. > >Talking of quick explanations, I would love to see kinds and singleton >types explained in the same manner. You tried to explain singleton types >at page 13, but I find explanation provided by GHC documentation[1] to >be much more clear. As for kinds, it just puzzles me why you use the >term but don't explain it. > > 1. http://hackage.haskell.org/trac/ghc/wiki/TypeNats/Basics > >The same goes for type families - while I was able to quickly look up >definition of singleton types, I failed to comprehend basics of type >families by reading Haskell Wiki. I ended up pretending that type >families are just type-level functions. > >I would love to see Yampa optimizations section expanded with more >interesting examples. Are there any? > >Last but not least, a few minor typos and errors I spotted: > >* at page 8, "Than we need to declare type instances..." should be "Then > we need..."; > >* probably due to excessive editing, parameters to repeatElem at page 13 > are in the different order than before; > >* at page 14, you state: > > > As in all binary search trees, for a particular node N c l x r > > values greater than x are stored in left sub-tree (in l) and values > > less than x are stored in right sub-tree (in r). > > But later on, your code contradict that statement by recursing to left > sub-tree when x we look for is less than value in the node, and to > right sub-tree when x is greater than value in the node. > >Thank you once again for a nice introduction to GADTs! > >-- >Regards, >Alexander Batischev > >PGP key 356961A20C8BFD03 >Fingerprint: CE6C 4307 9348 58E3 FD94 A00F 3569 61A2 0C8B FD03 > >
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