cabal-extras

A tool suite to aid Haskell development using cabal-install. There are four tools in this repository:

• cabal-env: An experiment on what cabal install --lib could be.
• cabal-diff: Compare API of different package versions
• cabal-bundler: (ab)use cabal-install solver to build standalone installation bundles
• cabal-deps: An experiment on what cabal outdated could be.
• cabal-store-check: A naive tool to try to repair cabal's nix-store

All tools are highly experimental, although I (Oleg Grenrus) use them daily.

There's also cabal-fmt, a .cabal file formatter, but it's more standalone tool.

Installation

To install individual executables from this repository,

1. Make sure you have GHC-8.2 and cabal-install-3.0 or later installed.
2. Clone it with git clone https://github.com/phadej/cabal-extras.git
3. Install individual executables with make install-cabal-env, make install-cabal-deps etc.

You can pass flags to cabal install by setting INSTALL_FLAGS, e.g.

make INSTALL_FLAGS="--installdir $HOME/bin --install-method copy" install-cabal-env

Executables

cabal-bundler

TBW

cabal-diff

TBW

cabal-deps

TBW

cabal-env

Synopsis

$ cabal-env optics
$ ghci
Prelude> import Optics
Prelude Optics>

TBW

cabal-store-check

This is a small script which can find some broken packages in cabal nix-store. It's a proof-of-concept of

• https://gitlab.haskell.org/ghc/ghc/merge_requests/2284
• haskell/cabal#6060

Synopsis

# Check if store package db is inconsistent
$ cabal-store-check
...
[   0.64132] error: haskell-ci-0.3.20190327-98543f1828739a9ad62f8722220f5d812f7f4a13f6fe2745a286c227593452b9 interface file for HaskellCI is missing
...

# You can remove broken packages with, which would repair the state
$ cabal-store-check --repair

cabal-store-gc

This is another small script to reduce size of cabal's nix-store.

Synopsis

# Add possible current projects dependencies as in direct root,
# and print reclaiming information
$ cabal-store-gc
...
...
[  16.89166] info: 262 components are referenced from the roots
[  16.89714] info: 183 components are in the store
[  16.89726] info: 393 components can be removed from the store
[  17.71338] info: 2328 MB can be freed

# If you want to perform the cleanup
$ cabal-store-gc --collect

# For more information, see
$ cabal-store-gc --help

Roots

There are three kind of roots, which retain the packages in the store:

• executables in installdir. These are automatic roots.
• packages references from environments in ~/.ghc/.../environments/.... These are also automatic roots.
• indirect roots, which are links from ~/.cabal/store/roots to plan.jsons elsewhere in the file system. Indirect links allow to retain development project dependencies. New indirect roots can be added with --add-project-root or --add-root actions.