This file contains a summary of changes to Haskell.nix and `nix-tools`
that will impact users.

## Oct 31, 2020
* Passing `tools.hoogle` to `shellFor` with a value suitable for `haskel-nix.tool` will
  use the specified `hoogle` inside `shellFor`. This allows for materialization
  of `hoogle`.

## Oct 28, 2020
* Passing `compiler-nix-name` to project functions for `stack.yaml`
  based projects now overrides the compiler used (was ignored before).

## Sep 8, 2020
* Added the ability to generate coverage reports for packages and
  projects.
* Added the `doCoverage` module option that allows users to choose
  packages to enable coverage for.
* Added a `doCoverage` flag to the component builder that outputs HPC
  information when coverage is enabled.
* Added test for coverage.

## July 21, 2020
* Removed `components.all`, use `symlinkJoin` on components.exes or
 `shellFor` if you need a shell.
* Added `components` argument to `shellFor`.

## July 21, 2020
* Added GHC 8.8.4 and replaced 8.8.3 in tests and as the ghc
  used to build nix-tools for stack projects.

## July 20, 2020
* Changed `haskell-nix.roots` and `p.roots` to single derivations.

## July 8, 2020
* Removed `sources.nixpkgs-default`, use `sources.nixpkgs` instead.
* Removed `./nixpkgs` directory, use  `(import ./. {}).sources`
  or `./nix/sources.nix` instead.
* Removes V1 interface for details on how to fix old code see:
    https://github.com/input-output-hk/haskell.nix/issues/709
* Removed defaultCompilerNixName.
* cabalProject, cabalProject', hackage-project and hackage-package
  now require a `compiler-nix-name` argument.
* `haskell-nix.tool` and `.tools` now require a `compiler-nix-name` argument.
  New functions `p.tool` and `p.tools` (where p is a project) do not.
  Like `shellFor { tools = ... }` they will use the compiler nix name
  from the project (including stack projects where it is derived from
  the resolver).
* `haskell-nix.alex` and `haskell-nix.happy` have been removed. Use
  `p.tool "alex" "3.2.5"` or `shellFor { tools = { alex = "3.2.5"; } }`.
* `haskell-nix.nix-tools` -> `haskell-nix.nix-tools.ghc883` (it includes
  the hpack exe now).
* `haskell-nix.cabal-install` ->
  `p.tool "cabal" "3.2.0.0"` or `shellFor { tools = { cabal = "3.2.0.0"; } }`
* `haskell-nix.haskellNixRoots` -> `haskell-nix.roots ghc883` or `p.roots`

## June 25, 2020
* Haddock docs are now built in their own derivation when needed (not as part
  of the component build).
  They should build automatically when something (such as `shellFor`) attempts
  to accesses the `.doc` attribute of component.

## December 27, 2019
* Fix overlays/bootstrap.nix to provide LLVM 6, not LLVM 5, to ghc-8.6.X compilers.

## November 18, 2019
  * Changed the `cleanSourceHaskell` to accept an attrset of `src` and
    (optional) `name` parameters. This allows you to keep the source
    derivation name constant, so that your builds are always
    cached. Usage of `cleanSourceHaskell` will need to be updated.

## October 12, 2019
 * [`shellFor`](https://input-output-hk.github.io/haskell.nix/reference/library/#shellfor) no longer sets `CABAL_CONFIG` by default.
   This avoids surprising users, but means that Cabal may select a plan which is different to your Haskell.nix package set.
   If you would like the old behaviour, use `shellFor { exactDeps = true; }`.

## August 9, 2019
 * Add the [`haskellLib.collectComponents`](https://input-output-hk.github.io/haskell.nix/reference/library/#haskellLib) function.

## June 21, 2019
 * Add `ghcWithPackages` and `ghcWithHoogle` to hsPkgs ([documentation](https://input-output-hk.github.io/haskell.nix/reference/library/#package-set-functions).
 * Benchmark components can now build successfully.
 * Reduced the closure bloat of nix-tools, and added closure size limit to CI.
 * Added more reference documentation and set up auto-generated
   documentation for [Module Options](https://input-output-hk.github.io/haskell.nix/reference/modules/).
 * Miscellaneous bug fixes.

## June 7, 2019
  * Several additions to the [documentation](https://input-output-hk.github.io/haskell.nix/).
    * More information about getting nix-tools, Haskell.nix, pinning.
    * Updates the stack-to-nix and cabal-to-nix guides.
    * Adds a section on development environments.
    * Adds a little information about cross compilation.
    * Adds a (partially complete) reference section (command line manuals, library reference).
    * Symlinks the changelog into the documentation pages.

## May 29, 2019
  * Added `shellFor` function to package set.

## May 28, 2019
  * Added `snaphots` and `haskellPackages` attributes to the
    Haskell.nix top-level.

## May 22, 2019
  * Add the `cleanSourceHaskell` utility function to the Haskell.nix
    top-level.

## May 21, 2019
  * Add the `callCabalProjectToNix` function, which uses "import from
    derivation" (IFD) so that nix-tools doesn't need to be run
    manually.
  * The `hackage.nix` update process has changed, so that Cabal index
    state hashes are also included in the generated repo.

## May 20, 2019
  * Remove Travis CI in favour of Buildkite.

## May 17, 2019
  * Add the `callStackToNix` function, which uses "import from
    derivation" (IFD) so that `stack-to-nix` doesn't need to be run
    manually.

## Mar 15, 2019
  * `overlays` was renamed to `extras` in
    [#79](https://github.com/input-output-hk/haskell.nix/pull/79)
    to prevent confusion between the notion of Nix overlays.

    Therefore `plan-pkgs` and `stack-pkgs` as generated by `plan-to-nix` and `stack-to-nix` will
    expose `extras` instead of `overlay`. Similarly `mkStackPkgSet`, `mkPkgSet` and `mkCabalProjectPkgSet`
    take a `pkg-def-extras` instead of `pkg-def-overlay` argument.  If you are using `iohk-nix`, the
    `iohk-overlay` was parameter was renamed to `iohk-extras`.