421 lines
12 KiB
Markdown
421 lines
12 KiB
Markdown
% GHCup
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% Julian Ospald
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% June 07, 2024
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# Introduction
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## What is GHCup?
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## State of 2019
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::: incremental
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* stack is the only "Haskell Installer"
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* no unified alternative for cabal users
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* distro packages, nix, manual installs, ...
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* 🤮
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:::
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## How it started
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::: incremental
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* 🤹 small team at work (Capital Match), using different platforms
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- originally used stack
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- cabal distro packages constantly out of date
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* 🦾 first version was 165 LOC
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- Posix shell
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* {#id .class height=32px} only supported linux and mac
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* {#id .class height=32px} inspired by **rustup**
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:::
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## GHCup today
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[Haskell Survey 2022](https://taylor.fausak.me/2022/11/18/haskell-survey-results/#s2q1):
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. . .
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- over **17k** LOC Haskell
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- supports all platforms: Linux, Windows, macOS, FreeBSD
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## GHCup and haskell.org
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The default installer:
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. . .
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* provides infrastructure (home page, downloads)
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## GHCup and the Haskell Foundation
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::: incremental
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* affiliation: [https://haskell.foundation/affiliates/](https://haskell.foundation/affiliates/)
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* pays for CI
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* pays consultants to assist the project
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:::
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# Philosophy
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## What is a good installer?
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::: incremental
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* it installs (just that)
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- everywhere
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* intuitive interface
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- `ghcup install ghc`
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* good documentation
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- but you shouldn't have to read it
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* get out of the way
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- has no self-fulfilling purpose
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:::
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## Goals and principles
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::: incremental
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- ☮️ unification
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- unix principles
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- 🛠️ do one thing and do it well
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- ⚗️ pipes, compose stdout and stdin (re-usable)
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- 🎁 good re-distribution
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- 🛣️ user experience
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:::
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## What is GHCup (simplified)?
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```sh
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curl -s -L 'https://downloads.haskell.org/~ghc/9.6.5/ghc-9.6.5-x86_64-fedora33-linux.tar.xz' |
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tar -xJ -C /tmp &&
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cd /tmp/ghc-9.6.5-x86_64-unknown-linux/ &&
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./configure --prefix="$HOME/.local" &&
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make install &&
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rm -rf /tmp/ghc-9.6.5-x86_64-unknown-linux/
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```
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## What is GHCup really?
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* [https://hasufell.github.io/posts/2023-11-14-ghcup-is-not-an-installer.html](https://hasufell.github.io/posts/2023-11-14-ghcup-is-not-an-installer.html)
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::: incremental
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* {#id .class width=32 height=32px} installer
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* {#id .class width=32 height=32px} distribution channel
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* {#id .class width=32 height=32px} feedback channel
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* {#id .class width=32 height=32px} testing/QA gateway
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* {#id .class width=32 height=32px} provider of sane defaults (e.g. "recommended" GHC version)
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* {#id .class width=32 height=32px} glue for holistic toolchain experience
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- VSCode, stack, cabal-install integration
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* {#id .class width=32 height=32px} CI provisioning (e.g. github actions)
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:::
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# Relationships
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## Upstream (dependencies)
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- supported tools
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- GHC
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- Cabal
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- HLS
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- Stack
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. . .
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- decisions that affect us
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- release frequency
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- upstream CI
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- platform support
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- binary distributions (the `.tar.gz`/`.zip`)
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## Downstream (dependents)
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- {#id .class height=32px} Haskell developers
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- beginners, advanced, students, companies
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- {#id .class width=32 height=32px} end users (e.g. compiling pandoc from source)
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- {#id .class width=32 height=32px} GitHub CI
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- GitHub images, Haskell repos
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- 🪞 mirrors
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- [sjtug](https://mirror.sjtu.edu.cn/docs/ghcup)
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- 🧰 tools
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- [vscode-haskell](https://github.com/haskell/vscode-haskell), [Haskell playground](https://play.haskell.org/), [nvim-lsp-installer](https://github.com/williamboman/nvim-lsp-installer)
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# The installer in detail
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## How does it work?
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* **Architectural components**
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- {#id .class height=32px} bootstrap scripts
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- {#id .class height=32px} ghcup binary (compiled)
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- {#id .class height=32px} ghcup-metadata
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. . .
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* **Logical components**
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- {#id .class height=32px} cli interface
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- {#id .class height=32px} file layout / installation destination
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- {#id .class height=32px} bindist selection
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- {#id .class height=32px} tui interface
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- {#id .class height=32px} configuration
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## Basic CLI (context)
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* **Architectural components**
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- [ ] {#id .class height=32px} bootstrap scripts
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- [x] {#id .class height=32px} ghcup binary (compiled)
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- [ ] {#id .class height=32px} ghcup-metadata
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* **Logical components**
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- [x] {#id .class height=32px} cli interface
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- [ ] {#id .class height=32px} file layout / installation destination
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- [ ] {#id .class height=32px} bindist selection
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- [ ] {#id .class height=32px} tui interface
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- [ ] {#id .class height=32px} configuration
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## Basic CLI
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::: incremental
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* show all available tools / versions
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```sh
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ghcup list
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```
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* install a tool
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```sh
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ghcup install ghc latest
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```
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* make a tool version the default
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```sh
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ghcup set ghc latest
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```
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* remove a tool version
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```sh
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ghcup rm ghc 9.10.1
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```
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:::
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## File layout (context)
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* **Architectural components**
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- [ ] {#id .class height=32px} bootstrap scripts
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- [x] {#id .class height=32px} ghcup binary (compiled)
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- [ ] {#id .class height=32px} ghcup-metadata
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* **Logical components**
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- [ ] {#id .class height=32px} cli interface
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- [x] {#id .class height=32px} file layout / installation destination
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- [ ] {#id .class height=32px} bindist selection
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- [ ] {#id .class height=32px} tui interface
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- [ ] {#id .class height=32px} configuration
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## File layout
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::: incremental
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* root dir
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```sh
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$ ls ~/.ghcup
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📁bin 📁ghc 📁hls
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📁cache 📁db 📁logs 📁tmp 🗑️trash 📄config.yaml 📄env
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```
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* GHC and HLS are installed into sub-directories
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```sh
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$ ls ~/.ghcup/ghc
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📁8.10.7 📁9.0.2 📁9.2.8
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```
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* bin directory is mostly symbolic links (compare with [update-alternatives](https://man7.org/linux/man-pages/man1/update-alternatives.1.html))
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```sh
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$ ls ~/.ghcup/bin
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📄ghcup
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🔗cabal 📄cabal-3.10.3.0
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🔗ghc 🔗ghc-8.10 🔗ghc-8.10.7 🔗ghc-9.0 🔗ghc-9.0.2 🔗ghc-9.2 🔗ghc-9.2.8
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```
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:::
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## Bindist selection (context)
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* **Architectural components**
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- [ ] {#id .class height=32px} bootstrap scripts
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- [x] {#id .class height=32px} ghcup binary (compiled)
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- [x] {#id .class height=32px} ghcup-metadata
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* **Logical components**
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- [ ] {#id .class height=32px} cli interface
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- [ ] {#id .class height=32px} file layout / installation destination
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- [x] {#id .class height=32px} bindist selection
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- [ ] {#id .class height=32px} tui interface
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- [ ] {#id .class height=32px} configuration
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## Bindist selection (sysinfo)
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**Gather system information:**
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::: incremental
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* module `GHCup.Platform`
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* `System.Info.arch` and `System.Info.os` (compile-time strings)
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* distro detection mostly via `/etc/os-release`
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- specified by [freedesktop.org](https://www.freedesktop.org/software/systemd/man/latest/os-release.html)
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- using [os-release](https://hackage.haskell.org/package/os-release) package for parsing
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:::
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## Bindist selection (mapping)
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**Map binaries to systems:**
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::: incremental
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- binary compatibility (platform, distro, distro version)
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- finite set of binaries
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- statically linked GHC?
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- static mapping in [ghcup-metadata YAML files](https://github.com/haskell/ghcup-metadata/blob/develop/ghcup-0.0.8.yaml)
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- Tool -> Version -> Architecture -> Platform/Distro -> binary URL
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- mapping based on binary compatibility
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- [https://gitlab.haskell.org/ghc/ghc/-/wikis/platforms/linux](https://gitlab.haskell.org/ghc/ghc/-/wikis/platforms/linux)
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- alternative dynamic logic (utilizing `ldconfig -p` output)
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- for stack compatibility
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- updated on every release
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- "channels"
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:::
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## Installation flow
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{#id .class height=500px}
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## TUI interface (context)
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* **Architectural components**
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- [ ] {#id .class height=32px} bootstrap scripts
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- [x] {#id .class height=32px} ghcup binary (compiled)
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- [ ] {#id .class height=32px} ghcup-metadata
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* **Logical components**
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- [ ] {#id .class height=32px} cli interface
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- [ ] {#id .class height=32px} file layout / installation destination
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- [ ] {#id .class height=32px} bindist selection
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- [x] {#id .class height=32px} tui interface
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- [ ] {#id .class height=32px} configuration
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## TUI interface
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{#id .class height=550px}
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## Configuration (context)
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* **Architectural components**
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- [X] {#id .class height=32px} bootstrap scripts
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- [x] {#id .class height=32px} ghcup binary (compiled)
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- [x] {#id .class height=32px} ghcup-metadata
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* **Logical components**
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- [ ] {#id .class height=32px} cli interface
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- [ ] {#id .class height=32px} file layout / installation destination
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- [ ] {#id .class height=32px} bindist selection
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- [ ] {#id .class height=32px} tui interface
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- [x] {#id .class height=32px} configuration
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## Configuration
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::: incremental
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* Types of configuration:
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- environment variables
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- cli switches / TUI options
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- config file (`~/.ghcup/config.yaml`)
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* e.g.
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- env: `GHCUP_INSTALL_BASE_PREFIX` (default `$HOME`)
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- cli: `ghcup install ghc -u <url> <version>`
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- config: `url-source` (selecting and mixing "channels")
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- file/http/https URI
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- `GHCupURL`
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- `StackSetupURL`
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:::
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## Phew
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{#id .class height=550px}
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# Distribution
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## What is distribution?
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* QA gate between "upstream" and "downstream"
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* trust relationship (with upstream and downstream)
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* release selection and defaults
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* binary distribution
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## What happens on e.g. a GHC release
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- testing and inspection of bindists
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- manual
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- automated at [github.com/haskell/ghcup-metadata](https://github.com/haskell/ghcup-metadata/blob/develop/.github/workflows/bindists.yaml)
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- fixing bindists
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- building additional bindists (e.g. FreeBSD)
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. . .
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- forks at [github.com/stable-haskell](https://github.com/stable-haskell)
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- builds cabal, stack and HLS binaries
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- GHC TBD
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## The "recommended" versions (defaults)
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* community adoption (both industry and "open source")
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* stack LTS
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* HLS support
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* known issues and regressions
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* GHC HQs opinion and support window
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* must be consistent across platforms
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# Contributing
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## How to contribute
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::: incremental
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- loose project structure (BDFL)
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- discuss early
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- repositories
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- [github.com/haskell/ghcup-hs](https://github.com/haskell/ghcup-hs): documentation, bootstrap-scripts, ghcup exe
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- [github.com/haskell/ghcup-metadata](https://github.com/haskell/ghcup-metadata): bindist mapping (YAML), bindist testing
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- build with cabal/stack
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- communication
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- [#haskell-ghcup](https://kiwiirc.com/nextclient/irc.libera.chat/?nick=Guest%7C?##haskell-ghcup) on libera IRC
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- [#ghcup:matrix.org](https://matrix.to/#/#ghcup:matrix.org) (bridged with IRC)
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- [github issues](https://github.com/haskell/ghcup-hs/issues)
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- [haskell discourse](https://discourse.haskell.org/) (interacting with the community)
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:::
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## Getting started
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Head over to [https://github.com/haskell/ghcup-hs/issues/1074](https://github.com/haskell/ghcup-hs/issues/1074) (`zurihac` labeled issue).
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## Advanced topics
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- bootstrap scripts
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- windows and MSYS2
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- security
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- HLS/GHC interaction
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- reproducibility
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- stack integration
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- bindist work (curation)
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- isolated installs
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- mirrors
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