November 2020 - Glasgow-haskell-users

[ANNOUNCE] Glasgow Haskell Compiler 9.0.1-alpha1 released
by Ben Gamari 07 Dec '20

07 Dec '20

Hello all, The GHC team is very pleased to announce the availability of the first alpha release in the GHC 9.0 series. Source and binary distributions are available at the usual place: https://downloads.haskell.org/ghc/9.0.1-alpha1/ This first alpha comes quite a bit later than expected. However, we have done a significant amount of testing on this pre-release and therefore hope to be able to move forward quickly with a release candidate next week and with a final release in mid-October. GHC 9.0.1 will bring a number of new features: * A first cut of the new LinearTypes language extension [1], allowing use of linear function syntax and linear record fields. * A new bignum library (ghc-bignum), allowing GHC to be more easily used with integer libraries other than GMP. * Improvements in code generation, resulting in considerable performance improvements in some programs. * Improvements in pattern-match checking, allowing more precise detection of redundant cases and reduced compilation time. * Implementation of the "simplified subsumption" proposal [2] simplifying the type system and paving the way for QuickLook impredicativity in GHC 9.2. * Implementation of the QualifiedDo extension [3], allowing more convenient overloading of `do` syntax. * Improvements in compilation time. And many more. See the release notes [4] for a full accounting of the changes in this release. Do note that there are a few things that we expect will change before the final release: * We expect to sort out a notarization workflow for Apple Darwin, allowing our binary distributions to be used on macOS Catalina without hassle. Until this has been sorted out Catalina users can exempt the current macOS binary distribution from the notarization requirement themselves by running `xattr -cr .` on the unpacked tree before running `make install`. * We will likely transition the Alpine binary distribution to be fully statically-linked, providing a convenient, distribution-independent packaging option for Linux users. * We will be merging a robust solution for #17760 which will introduce a new primitive, `keepAlive#`, to the `base` library, subsuming most uses of `touch#`. As always, do test this release and open tickets for whatever issues you encounter. To help with this, we will be publishing a blog post describing use of our new `head.hackage` infrastructure to ease testing of larger projects with Hackage dependencies later this week. Cheers, - Ben [1] https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0111-l… [2] https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0287-s… [3] https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0216-q… [4] https://downloads.haskell.org/ghc/9.0.1-alpha1/docs/html/users_guide/9.0.1-…

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Обучение языку, работа с компилятором chg
by Инна Бородина 01 Nov '20

01 Nov '20

Здравствуйте! Я совершенный и полный новичек в любом программировании. Я не могу понять из официальных руководств как установить cabal и зачем нужна эта программа. Я не понимаю как установить на мой ноутбук дистрибутивы. Я сохранила двоичный вариант. Виндос 10. Не понятно как с клавиатуры установить обратные кавычки. В во вставках ограниченной свободной лицензии Офиса их нет. В эмодзи-вставка слишком много типов обратных кавычек. Мне остается только перебор вариантов? Русская буква "ё" на моей клавиатуре дает знак тождества. Возможно, я все время ощибаюсь с раскладкой клавиатуры. Может цифровой код подскажите? Инна Бородина

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Language extension histories
by David Feuer 01 Nov '20

01 Nov '20

I'm working on some code I want to be compatible with multiple GHC versions and I'm trying to figure out which language extensions I can reasonably use. I definitely need usable fancy pattern synonyms (not the bare-bones ones in 7.8). So that should set a lower bound, but I don't remember where. 7.10? 8.0? I'd also *like* to use an injective type family, but I can work around that pretty easily with a data family if necessary. When did PatternSynonyms and TypeFamilyDependencies each become reasonably usable?

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