oh-my-zsh/plugins/cabal/cabal.plugin.zsh

function cabal_sandbox_info() {
    cabal_files=(*.cabal(N))
    if [ $#cabal_files -gt 0 ]; then
        if [ -f cabal.sandbox.config ]; then
            echo "%{$fg[green]%}sandboxed%{$reset_color%}"
        else
            echo "%{$fg[red]%}not sandboxed%{$reset_color%}"
        fi
    fi
}

function _cabal_commands() {
    local ret=1 state
    _arguments ':subcommand:->subcommand' && ret=0

    case $state in
      subcommand)
        subcommands=(
          "bench:Run the benchmark, if any (configure with UserHooks)"
          "build:Compile all targets or specific target."
          "check:Check the package for common mistakes"
          "clean:Clean up after a build"
          "copy:Copy the files into the install locations"
          "configure:Prepare to build the package"
          "exec:Run a command with the cabal environment"
          "fetch:Downloads packages for later installation"
          "freeze:Freeze dependencies."
          "get:Gets a package's source code"
          "haddock:Generate Haddock HTML documentation"
          "help:Help about commands"
          "hscolour:Generate HsColour colourised code, in HTML format"
          "info:Display detailed information about a particular package"
          "init:Interactively create a .cabal file"
          "install:Installs a list of packages"
          "list:List packages matching a search string"
          "register:Register this package with the compiler"
          "repl:Open an interpreter session for the given target"
          "report:Upload build reports to a remote server"
          "run:Runs the compiled executable"
          "sandbox:Create/modify/delete a sandbox"
          "sdist:Generate a source distribution file (.tar.gz)"
          "test:Run the test suite, if any (configure with UserHooks)"
          "unpack:Unpacks packages for user inspection"
          "update:Updates list of known packages"
          "upload:Uploads source packages to Hackage"
        )
        _describe -t subcommands 'cabal subcommands' subcommands && ret=0
    esac

    return ret
}

compdef _cabal_commands cabal

function _cab_commands() {
    local ret=1 state
    _arguments ':subcommand:->subcommand' && ret=0

    case $state in
      subcommand)
        subcommands=(
          "sync:Fetch the latest package index"
          "install:Install packages"
          "uninstall:Uninstall packages"
          "installed:List installed packages"
          "configure:Configure a cabal package"
          "build:Build a cabal package"
          "clean:Clean up a build directory"
          "outdated:Display outdated packages"
          "info:Display information of a package"
          "sdist:Make tar.gz for source distribution"
          "upload:Uploading tar.gz to HackageDB"
          "get:Untar a package in the current directory"
          "deps:Show dependencies of this package"
          "revdeps:Show reverse dependencies of this package"
          "check:Check consistency of packages"
          "genpaths:Generate Paths_<pkg>.hs"
          "search:Search available packages by package name"
          "add:Add a source directory"
          "test:Run tests"
          "bench:Run benchmarks"
          "doc:Generate manuals"
          "ghci:Run GHCi (with a sandbox)"
          "init:Initialize a sandbox"
          "help:Display the help message of the command"
        )
        _describe -t subcommands 'cab subcommands' subcommands && ret=0
    esac

    return ret
}

command -v cab >/dev/null 2>&1 && { compdef _cab_commands cab }