ghcup-talk/GHCup.md

% GHCup % Julian Ospald % June 07, 2024

GHCup

Intro

Haskell Survey 2022

Intro (pt. 2)

haskell.org:

What is GHCup (simplified)?

curl -s -L 'https://downloads.haskell.org/~ghc/9.6.5/ghc-9.6.5-x86_64-fedora33-linux.tar.xz' |
  tar -xJ -C /tmp                              &&
  cd /tmp/ghc-9.6.5-x86_64-unknown-linux/      &&
  ./configure --prefix="$HOME/.local"          &&
  make install                                 &&
  rm -rf /tmp/ghc-9.6.5-x86_64-unknown-linux/

How it started

::: incremental

• 🤹 small team at work on different platforms
• 🧑‍💻 SHELL + POSIX
• 🦾 first version was 165 LOC
• 🙏 only installer at that time was stack

:::

Goals

::: incremental

• ☮️ unification
• unix principles
  • 🛠️ do one thing and do it well
  • ⚗️ pipes, compose stdout and stdin
• 🎁 good re-distribution
• 🛣️ user experience (get out of the way)

:::

What is GHCup really?

• https://hasufell.github.io/posts/2023-11-14-ghcup-is-not-an-installer.html

::: incremental

• {#id .class width=32 height=32px} installer
• {#id .class width=32 height=32px} distribution channel
• {#id .class width=32 height=32px} feedback channel
• {#id .class width=32 height=32px} testing/QA gateway
• {#id .class width=32 height=32px} provider of sane defaults (e.g. "recommended" GHC version)
• {#id .class width=32 height=32px} glue for holistic toolchain experience
  • stack integration
  • VSCode integration
  • cabal-install integration
• {#id .class width=32 height=32px} CI provisioning (e.g. github actions)

:::

Upstream

Supported tools/dependencies:

::: incremental

• GHC
• Cabal
• HLS
• Stack

:::

Downstream

Users:

::: incremental

• {#id .class height=32px} Haskell developers
  • beginners / advanced
  • student courses
  • companies
• {#id .class width=32 height=32px} end users (e.g.compiling pandoc from source)
• {#id .class width=32 height=32px} GitHub CI
  • GitHub images
  • Haskell repos
• 🪞 mirrors
  • sjtug
• 🧰 tools
  • vscode-haskell
  • Haskell playground
  • nvim-lsp-installer

:::

How does it work?

Components:

::: incremental

• {#id .class height=32px} cli interface
• {#id .class height=32px} file layout / installation destination
• {#id .class height=32px} bindist selection
• 🧱 tui interface

:::

Basic CLI

::: incremental

• show all available tools / versions

  ghcup list
  

• install a tool

  ghcup install ghc latest
  

• make a tool version the default

  ghcup set ghc latest
  

• remove a tool version

  ghcup rm ghc 9.10.1
  

:::

Where does it install?

::: incremental

• root dir

  $ ls ~/.ghcup
  bin  cache  config.yaml  db  env  ghc  hls  logs  share  tmp  trash
  

• GHC and HLS are installed into sub-directories

  $ ls ~/.ghcup/ghc
  8.10.7	9.0.2	9.2.8
  

• bin directory is mostly symbolic links

  $ ls ~/.ghcup/bin
  ghcup
  cabal cabal-3.10.3.0
  ghc ghc-8.10 ghc-8.10.7 ghc-9.0 ghc-9.0.2 ghc-9.2 ghc-9.2.8
  

:::

Bindist selection