Port hie README partially

README.md

@@ -14,11 +14,277 @@ background](https://neilmitchell.blogspot.com/2020/01/one-haskell-ide-to-rule-th
 
 This is *very* early stage software.
 
-To play along at home, do a recursive `git clone`.
+- [Haskell Language Server (HLS)](#haskell-language-server)
+  - [Installation](#installation)
+    - [Installation from source](#installation-from-source)
+      - [Common pre-requirements](#common-pre-requirements)
+      - [Linux-specific pre-requirements](#linux-specific-pre-requirements)
+      - [Windows-specific pre-requirements](#windows-specific-pre-requirements)
+      - [Download the source code](#download-the-source-code)
+      - [Building](#building)
+        - [Install via cabal](#install-via-cabal)
+        - [Install specific GHC Version](#install-specific-ghc-version)
+  - [Project Configuration](#project-configuration)
+  - [Contributing](#contributing)
+    - [It's time to join the project!](#its-time-to-join-the-project)
 
-Initial effort is to understand how plugins can be supported in a modular way.
+## Installation
 
-Builds with stack and cabal, using GHC 8.6.5
+For now only installation from source is supported.
+
+### Installation from source
+
+#### Common pre-requirements
+
+- `stack` or `cabal` must be in your PATH
+  - You need stack version >= 2.1.1 or cabal >= 2.4.0.0
+- `git` must be in your PATH
+- The directory where `stack`or `cabal` put the binaries must be in you PATH:
+  - For stack you can get it with `stack path --local-bin`
+  - For cabal it is by default `$HOME/.cabal/bin` in linux and `%APPDATA%\cabal\bin` in windows.
+
+Tip: you can quickly check if some command is in your path by running the command.
+If you receive some meaningful output instead of "command not found"-like message
+then it means you have the command in PATH.
+
+#### Linux-specific pre-requirements
+
+On Linux you will need install a couple of extra libraries (for Unicode ([ICU](http://site.icu-project.org/)) and [NCURSES](https://www.gnu.org/software/ncurses/)):
+
+**Debian 9/Ubuntu 18.04 or earlier**:
+
+```bash
+sudo apt install libicu-dev libtinfo-dev libgmp-dev
+```
+
+**Debian 10/Ubuntu 18.10 or later**:
+
+```bash
+sudo apt install libicu-dev libncurses-dev libgmp-dev
+```
+
+**Fedora**:
+
+```bash
+sudo dnf install libicu-devel ncurses-devel # also zlib-devel if not already installed
+```
+
+#### Windows-specific pre-requirements
+
+In order to avoid problems with long paths on Windows you can do either one of the following:
+
+1. Clone the `haskell-language-server` to a short path, for example the root of your logical drive (e.g. to
+   `C:\hls`). Even if you choose `C:\haskell-language-server` you could hit the problem. If this doesn't work or you want to use a longer path, try the second option.
+
+2. If the `Local Group Policy Editor` is available on your system, go to: `Local Computer Policy -> Computer Configuration -> Administrative Templates -> System -> Filesystem` set `Enable Win32 long paths` to `Enabled`. If you don't have the policy editor you can use regedit by using the following instructions [here](https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#enable-long-paths-in-windows-10-version-1607-and-later). You also need to configure git to allow longer paths by using unicode paths. To set this for all your git repositories use `git config --system core.longpaths true` (you probably need an administrative shell for this) or for just this one repository use `git config core.longpaths true`.
+
+In addition make sure `haskell-language-server.exe` is not running by closing your editor, otherwise in case of an upgrade the executable can not be installed.
+
+#### Download the source code
+
+```bash
+git clone https://github.com/haskell/haskell-language-server --recurse-submodules
+cd haskell-language-server
+```
+
+#### Building
+
+Note, on first invocation of the build script with stack, a GHC is being installed for execution.
+The GHC used for the `install.hs` can be adjusted in `./install/shake.yaml` by using a different resolver.
+
+Available commands can be seen with:
+
+```bash
+stack ./install.hs help
+```
+
+Remember, this will take time to download a Stackage-LTS and an appropriate GHC for build
+haskell-language-server the first time.
+
+##### Install via cabal
+
+The install-script can be invoked via `cabal` instead of `stack` with the command
+
+```bash
+cabal v2-run ./install.hs --project-file install/shake.project <target>
+```
+
+or using the existing alias script
+
+```bash
+./cabal-hls-install <target>
+```
+
+Running the script with cabal on windows requires a cabal version greater or equal to `3.0.0.0`.
+
+For brevity, only the `stack`-based commands are presented in the following sections.
+
+##### Install specific GHC Version
+
+Install haskell-language-server for the latest available and supported GHC version (and hoogle docs):
+
+```bash
+stack ./install.hs hls
+```
+
+Install haskell-language-server for a specific GHC version (and hoogle docs):
+
+```bash
+stack ./install.hs hls-8.8.3
+stack ./install.hs data
+```
+
+The Haskell Language Server can also be built with `cabal v2-build` instead of `stack build`.
+This has the advantage that you can decide how the GHC versions have been installed.
+To see what GHC versions are available, the command `cabal-hls-install ghcs` can be used.
+It will list all *supported* GHC versions that are on the path for build with their respective installation directory.
+If you think, this list is incomplete, you can try to modify the PATH variable, such that the executables can be found.
+Note, that the targets `hls` and `data` depend on the found GHC versions.
+
+An example output is:
+
+```bash
+> cabal-hls-install ghcs
+******************************************************************
+Found the following GHC paths:
+ghc-8.6.5: /opt/bin/ghc-8.6.5
+ghc-8.8.3: /opt/bin/ghc-8.8.3
+
+******************************************************************
+```
+
+If your desired ghc has been found, you use it to install haskell-language-server.
+
+```bash
+cabal-hls-install hls-8.6.5
+cabal-hls-install data
+```
+
+## Project Configuration
+
+**For a full explanation of possible configurations, refer to [hie-bios/README](https://github.com/mpickering/hie-bios/blob/master/README.md).**
+
+haskell-language-server has some limited support via hie-bios to detect automatically
+your project configuration and set up the environment for GHC.
+The plan is to improve it to handle most use cases.
+
+However, for now, the more reliable way is using a `hie.yaml` file in the root
+of the workspace to **explicitly** describe how to setup the environment.
+For that you need to know what *components* have your project and the path
+associated with each one. So you will need some knowledge about
+[stack](https://docs.haskellstack.org/en/stable/build_command/#components) or [cabal](https://cabal.readthedocs.io/en/latest/cabal-commands.html?#cabal-v2-build) components.
+
+You also can use [this utility](https://github.com/Avi-D-coder/implicit-hie
+) to generate automatically `hie.yaml` files for
+the most common stack and cabal configurations
+
+For example, to state that you want to use `stack` then the configuration file
+would look like:
+
+```yaml
+cradle:
+  stack:
+    component: "haskell-language-server:lib"
+```
+
+If you use `cabal` then you probably need to specify which component you want
+to use.
+
+```yaml
+cradle:
+  cabal:
+    component: "lib:haskell-language-server"
+```
+
+If you have a project with multiple components, you can use a cabal-multi
+cradle:
+
+```yaml
+cradle:
+  cabal:
+    - path: "./test/functional/"
+      component: "haskell-language-server:func-test"
+    - path: "./test/utils/"
+      component: "haskell-language-server:hls-test-utils"
+    - path: "./exe/Main.hs"
+      component: "haskell-language-server:exe:haskell-language-server"
+    - path: "./exe/Wrapper.hs"
+      component: "haskell-language-server:exe:haskell-language-server-wrapper"
+    - path: "./src"
+      component: "lib:haskell-language-server"
+    - path: "./ghcide/src"
+      component: "ghcide:lib:ghcide"
+    - path: "./ghcide/exe"
+      component: "ghcide:exe:ghcide"
+```
+
+Equivalently, you can use stack:
+
+```yaml
+cradle:
+  stack:
+    - path: "./test/functional/"
+      component: "haskell-language-server:func-test"
+    - path: "./exe/Main.hs"
+      component: "haskell-language-server:exe:haskell-language-server"
+    - path: "./exe/Wrapper.hs"
+      component: "haskell-language-server:exe:haskell-language-server-wrapper"
+    - path: "./src"
+      component: "haskell-language-server:lib"
+    - path: "./ghcide/src"
+      component: "ghcide:lib:ghcide"
+    - path: "./ghcide/exe"
+      component: "ghcide:exe:ghcide"
+```
+
+Or you can explicitly state the program which should be used to collect
+the options by supplying the path to the program. It is interpreted
+relative to the current working directory if it is not an absolute path.
+
+```yaml
+cradle:
+  bios:
+    program: ".hie-bios"
+```
+
+The complete configuration is a subset of
+
+```yaml
+cradle:
+  cabal:
+    component: "optional component name"
+  stack:
+    component: "optional component name"
+  bios:
+    program: "program to run"
+    dependency-program: "optional program to run"
+  direct:
+    arguments: ["list","of","ghc","arguments"]
+  default:
+  none:
+
+dependencies:
+  - someDep
+```
+
+## Contributing
+
+### It's time to join the project!
+
+:heart: Haskell tooling dream is near, we need your help! :heart:
+
+- Join [our IRC channel](https://webchat.freenode.net/?channels=haskell-ide-engine) at `#haskell-ide-engine` on `freenode`.
+- Fork this repo and hack as much as you can.
+- Ask @alanz or @hvr to join the project.
+
+### Hacking on haskell-language-server
+
+Haskell-language-server can be used on its own project.  We have supplied
+preset samples of `hie.yaml` files for stack and cabal, simply copy
+the appropriate template to `hie.yaml` and it should work.
+
+- `hie.yaml.cbl` for cabal
+- `hie.yaml.stack` for stack
 
 Two sample `hie.yaml` files are provided, `hie.yaml.stack` for stack
 usage, `hie.yaml.cbl` for cabal. Simply copy the relevant one to be