[Haskell-cafe] GHC 7.10 Prelude: we need your opinion

[Simon Peyton Jones]

|  What were the objections? Especially the principle ones?

Please read the info pages, which set out the arguments quite carefully.

Also, I spammed several email lists to ensure broad coverage, but it'd be best to debate on the libraries at haskell.org, rather than reply-to-all; that's what it's for.  (Which I failed to send the announcement to!  I'll fix that.)

Simon

|  -----Original Message-----
|  From: Miguel Mitrofanov [mailto:miguelimo38 at yandex.ru]
|  Sent: 10 February 2015 15:59
|  To: Simon Peyton Jones; haskell at haskell.org; Haskell Cafe (haskell-
|  cafe at haskell.org); GHC users; ghc-devs at haskell.org
|  Subject: Re: [Haskell-cafe] GHC 7.10 Prelude: we need your opinion
|  
|  What were the objections? Especially the principle ones?
|  
|  10.02.2015, 18:51, "Simon Peyton Jones" <simonpj at microsoft.com>:
|  > Haskell Friends
|  >
|  > This email asks for your help in deciding how to proceed with some
|  Prelude changes in GHC 7.10.  Please read on, but all the info is also
|  at the survey link, here: http://goo.gl/forms/XP1W2JdfpX.   Deadline
|  is 21 Feb.
|  >
|  > The ​Core Libraries Committee (CLC) is responsible for developing the
|  core libraries that ship with GHC. This is an important but
|  painstaking task, and we owe the CLC a big vote of thanks for taking
|  it on.
|  >
|  > For over a year the CLC has been working on integrating the Foldable
|  and Traversable classes (shipped in base in GHC 7.8) into the core
|  libraries, and into the Prelude in particular. Detailed planning for
|  GHC 7.10 started in the autumn of 2014, and the CLC went ahead with
|  this integration.
|  >
|  > Then we had a failure of communication.  As these changes affect the
|  Prelude, which is in scope for all users of Haskell, these changes
|  should be held to a higher bar than the regular libraries@ review
|  process.  However, the Foldable/Traversable changes were not
|  particularly well signposted. Many people have only recently woken up
|  to them, and some have objected (both in principle and detail).
|  >
|  > This is an extremely unfortunate situation. On the one hand we are
|  at RC2 for GHC 7.10, so library authors have invested effort in
|  updating their libraries to the new Prelude. On the other, altering
|  the Prelude is in effect altering the language, something we take
|  pretty seriously. We should have had this debate back in 2014, but
|  here we are, and it is unproductive to argue about whose fault it is.
|  We all share responsibility.
|  >
|  > We need to decide what to do now. A small group of us met by Skype
|  and we've decided to do this:
|  >
|  > ·         Push back GHC 7.10's release by at least a month, to late
|  March.  This delay also gives us breathing space to address an
|  unrelated show-stopping bug, Trac #9858.
|  >
|  > ·         Invite input from the Haskell community on which of two
|  approaches to adopt (this survey).  The main questions revolve around
|  impact on the Haskell ecosystem (commercial applications, teaching,
|  libraries, etc etc), so we want to ask your opinion rather than guess
|  it.
|  >
|  > ·         Ask Simon Marlow and Simon Peyton Jones to decide which
|  approach to follow for GHC 7.10.
|  >
|  > Wiki pages have been created summarizing these two primary
|  alternatives, including many more points and counter-points and
|  technical details:
|  >
|  > ·         Overall summary:
|  https://ghc.haskell.org/trac/ghc/wiki/Prelude710
|  >
|  > ·         Details of Plan List:
|  https://ghc.haskell.org/trac/ghc/wiki/Prelude710/List
|  >
|  > ·         Details of Plan FTP:
|  https://ghc.haskell.org/trac/ghc/wiki/Prelude710/FTP
|  >
|  > This survey invites your input on which plan we should follow. Would
|  you please
|  >
|  > ·         Read the details of the alternative plans on the three
|  wiki pages above
|  >
|  > ·         Add your response to the survey
|  >
|  > Please do read the background.  Well-informed responses will
|  help.  Thank you!
|  >
|  > DEADLINE: 21 February 2015
|  >
|  > Simon PJ
|  >
|  > ,
|  >
|  > _______________________________________________
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