5 ms·

GHC 8.0.1 is available

190 points by patrickmn 10y ago

MichaelBurge 10y ago
The FPComplete guys will probably have it up on Stackage in a few days. You can still use it by adding the tarball to your stack.yml, and maybe adding the 'allow-newer: true' flag: https://www.reddit.com/r/haskell/comments/4kdb74/is_a_stackage_snapshot_for_ghc_80_on_the_way/ https://www.reddit.com/r/haskell/comments/4kdb74/is_a_stacka... I'm looking forward to trying out the new debugging support: gdb was unusable with older GHCs. Implicit callstacks are cool: Remember that you can hide the parameter inside of your application's main monad: type MyApplicationM a = (?l :: CallStack) => StateT ConnectionPool IO a I've certainly run into a lot of the other stuff too. Good release all-around!
- bgamari 10y ago
  > I'm looking forward to trying out the new debugging support: gdb was unusable with older GHCs. Indeed; it should be slightly better now but as the documentation says, there are still plenty of rough edges. I certainly wouldn't recommend it for day-to-day use. I have a patch set in the works which ought to fix the remaining issues so hopefully 8.2 will finally be usable. However, in my experience the implicit callstack functionality along with the ability to provide callstacks from profiling information greatly reduces the need for DWARF unwinding for debugging (low-cost profiling, on the other hand, it may still be quite useful for).
TazeTSchnitzel 10y ago
* The introduction of the DuplicateRecordFields language extension, allowing multiple record types to declare fields of the same name Holy hell. Is this the end of the Haskell record field names problem? One of Haskell's great miseries has been that, because record field accessors are declared globally, you couldn't define records with fields of the same names: data Person = Person { name :: String, age :: Int } data Object = Object { name :: String, id :: UUID } -- error! `name` taken -- Edit: Info on the extension at: https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/DuplicateRecordFields https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedReco.... Looks like it creates ambiguity in some cases.
- dopu 10y ago
  As a recent beginner to Haskell, are there other big outstanding issues with the GHC to watch out for?
  - MichaelBurge 10y ago
    The record issue is a widespread inconvenience, but ultimately nothing more than an inconvenience. Most people just prepended the type in their fields: 'person_name' and 'object_name'. Some other issues might be: * The Prelude is hard to update for compatibility reasons, so it clashes with modern Haskell somewhat. A lot of projects will roll their own prelude and add 'NoImplicitPrelude' to the project options. * There's also this presentation: https://secure.plaimi.net/~alexander/tmp/pres/2016-05-11-why-haskell-sucks.html#1 https://secure.plaimi.net/~alexander/tmp/pres/2016-05-11-why... * Deploying Haskell programs to older corporate servers is doable, but not at all obvious. Stick with C, Bash, and older Perls(5.8.8 is on my router) for maximum portability, if you expect to deploy to servers with a 10 year old image.
    - iso-8859-1 10y ago
      Regarding deployment, why not just link statically? http://stackoverflow.com/a/5953787/309483 http://stackoverflow.com/a/5953787/309483
      - jeremyjh 10y ago
        This isn't portable with glibc. (It isn't for C/C++ programs, either). You can build GHC with musl libc and then make truly portable static binaries but it isn't that easy. https://www.reddit.com/r/haskell/comments/37m7q7/ghc_musl_easier_static_linking/ https://www.reddit.com/r/haskell/comments/37m7q7/ghc_musl_ea...
      - MichaelBurge 10y ago
        You can't link glibc statically for technical reasons. In some sense, this is the only problem I had. If there was a way to use an alternate libc, it would probably eliminate this issue entirely.
cm3 10y ago
The new Sphinx based documentation has many code sample boxes where the content overflows and the rectange is smaller than the text which doesn't fit into the rendered HTML/PDF. Is this a common issue with Sphinx?
- bgamari 10y ago
  Hmmm, I've noticed this in the PDF output but haven't yet seen anything similar in the HTML output. Could you point me at a specific example?
  - cm3 10y ago
    Rebuilding the latest release now, was referring to previous RCs. It may very well be just the PDF output. I'll check Sunday and report here.
    - cm3 10y ago
      One example: 3.2.8, the second code box about hsc2hs. HTML of the same section is fine. There must be a way to fix this in the pipeline. I mean, you cannot find each and all and try to manually adjust the text.
      - DasIch 10y ago
        I don't see the problem on this page[1]. In any case this would be an issue with the builder that turns the doctree into HTML, PDF or whatever. [1]: https://ghc.readthedocs.io/en/latest/8.0.1-notes.html#hsc2hs https://ghc.readthedocs.io/en/latest/8.0.1-notes.html#hsc2hs
        cm3 10y ago
        As I wrote, HTML is fine, PDF is not.
imh 10y ago
* Significant improvements in error message readability and content, including facilities for libraries to provide custom error messages, more aggressive warnings for fragile rewrite rules, and more helpful errors for missing imports. I'm really excited about this. Any push towards more decipherable error messages should be huge in increasing adoption (which leads to more awesome libraries and opportunities to use it for our day jobs). I still see plenty of errors that remind me of this post. https://izbicki.me/blog/error-messages-in-ghc-vs-g%2B%2B.html https://izbicki.me/blog/error-messages-in-ghc-vs-g%2B%2B.htm...

190 points by patrickmn 10y ago

The FPComplete guys will probably have it up on Stackage in a few days. You can still use it by adding the tarball to your stack.yml, and maybe adding the 'allow-newer: true' flag: https://www.reddit.com/r/haskell/comments/4kdb74/is_a_stackage_snapshot_for_ghc_80_on_the_way/ https://www.reddit.com/r/haskell/comments/4kdb74/is_a_stacka... I'm looking forward to trying out the new debugging support: gdb was unusable with older GHCs. Implicit callstacks are cool: Remember that you can hide the parameter inside of your application's main monad: type MyApplicationM a = (?l :: CallStack) => StateT ConnectionPool IO a I've certainly run into a lot of the other stuff too. Good release all-around!

bgamari 10y ago
> I'm looking forward to trying out the new debugging support: gdb was unusable with older GHCs. Indeed; it should be slightly better now but as the documentation says, there are still plenty of rough edges. I certainly wouldn't recommend it for day-to-day use. I have a patch set in the works which ought to fix the remaining issues so hopefully 8.2 will finally be usable. However, in my experience the implicit callstack functionality along with the ability to provide callstacks from profiling information greatly reduces the need for DWARF unwinding for debugging (low-cost profiling, on the other hand, it may still be quite useful for).

TazeTSchnitzel 10y ago

* The introduction of the DuplicateRecordFields language extension, allowing multiple record types to declare fields of the same name Holy hell. Is this the end of the Haskell record field names problem? One of Haskell's great miseries has been that, because record field accessors are declared globally, you couldn't define records with fields of the same names: data Person = Person { name :: String, age :: Int } data Object = Object { name :: String, id :: UUID } -- error! `name` taken -- Edit: Info on the extension at: https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/DuplicateRecordFields https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedReco.... Looks like it creates ambiguity in some cases.

dopu 10y ago
As a recent beginner to Haskell, are there other big outstanding issues with the GHC to watch out for?
- MichaelBurge 10y ago
  The record issue is a widespread inconvenience, but ultimately nothing more than an inconvenience. Most people just prepended the type in their fields: 'person_name' and 'object_name'. Some other issues might be: * The Prelude is hard to update for compatibility reasons, so it clashes with modern Haskell somewhat. A lot of projects will roll their own prelude and add 'NoImplicitPrelude' to the project options. * There's also this presentation: https://secure.plaimi.net/~alexander/tmp/pres/2016-05-11-why-haskell-sucks.html#1 https://secure.plaimi.net/~alexander/tmp/pres/2016-05-11-why... * Deploying Haskell programs to older corporate servers is doable, but not at all obvious. Stick with C, Bash, and older Perls(5.8.8 is on my router) for maximum portability, if you expect to deploy to servers with a 10 year old image.
  - iso-8859-1 10y ago
    Regarding deployment, why not just link statically? http://stackoverflow.com/a/5953787/309483 http://stackoverflow.com/a/5953787/309483
    - jeremyjh 10y ago
      This isn't portable with glibc. (It isn't for C/C++ programs, either). You can build GHC with musl libc and then make truly portable static binaries but it isn't that easy. https://www.reddit.com/r/haskell/comments/37m7q7/ghc_musl_easier_static_linking/ https://www.reddit.com/r/haskell/comments/37m7q7/ghc_musl_ea...
    - MichaelBurge 10y ago
      You can't link glibc statically for technical reasons. In some sense, this is the only problem I had. If there was a way to use an alternate libc, it would probably eliminate this issue entirely.

cm3 10y ago

The new Sphinx based documentation has many code sample boxes where the content overflows and the rectange is smaller than the text which doesn't fit into the rendered HTML/PDF. Is this a common issue with Sphinx?

bgamari 10y ago
Hmmm, I've noticed this in the PDF output but haven't yet seen anything similar in the HTML output. Could you point me at a specific example?
- cm3 10y ago
  Rebuilding the latest release now, was referring to previous RCs. It may very well be just the PDF output. I'll check Sunday and report here.
  - cm3 10y ago
    One example: 3.2.8, the second code box about hsc2hs. HTML of the same section is fine. There must be a way to fix this in the pipeline. I mean, you cannot find each and all and try to manually adjust the text.
    - DasIch 10y ago
      I don't see the problem on this page[1]. In any case this would be an issue with the builder that turns the doctree into HTML, PDF or whatever. [1]: https://ghc.readthedocs.io/en/latest/8.0.1-notes.html#hsc2hs https://ghc.readthedocs.io/en/latest/8.0.1-notes.html#hsc2hs
      - cm3 10y ago
        As I wrote, HTML is fine, PDF is not.

imh 10y ago

* Significant improvements in error message readability and content, including facilities for libraries to provide custom error messages, more aggressive warnings for fragile rewrite rules, and more helpful errors for missing imports. I'm really excited about this. Any push towards more decipherable error messages should be huge in increasing adoption (which leads to more awesome libraries and opportunities to use it for our day jobs). I still see plenty of errors that remind me of this post. https://izbicki.me/blog/error-messages-in-ghc-vs-g%2B%2B.html https://izbicki.me/blog/error-messages-in-ghc-vs-g%2B%2B.htm...