Powershell tab-completion script for stack

_stack.ps1

using namespace System.Management.Automation
using namespace System.Management.Automation.Language
Register-ArgumentCompleter -Native -CommandName 'stack' -ScriptBlock {
    param($wordToComplete, $commandAst)
    [string[]]$localCommand = @('"--bash-completion-enriched"')
    $hay = [System.Collections.Generic.List[string]]::new()
    foreach ($item in $commandAst.CommandElements) {
        $localCommand += '"--bash-completion-word"'
        $localCommand += """$item"""
        $hay.Add($item.ToString())
    }


    $localCommand += '"--bash-completion-index"'
    if ($wordToComplete.Equals("")) {
        $localCommand +=  '"' + $commandAst.CommandElements.Count +'"'
    }
    else {
        $localCommand += '"' + $hay.IndexOf($wordToComplete) + '"'
    }
    $inp = & '/path/to/stack' @localCommand
    [CompletionResult[]]$out = @()
    [string]$suffix =  if ($inp.Count -eq 1) {' '} else {""}
    foreach ($item in $inp) {
        $spl = $item.Split("`t")
        $show = $spl[0]
        $tooltip = if ($spl.Length -eq 1) { $spl[0] } else { $spl[1] }
        $crt = if ($show.StartsWith('-')) { [CompletionResultType]::ParameterName } else { [CompletionResultType]::ParameterValue }
        $out += [CompletionResult]::new($show + $suffix, $show, $crt, $tooltip)
    }
    $out
}

This script works best in pwsh >= 6 (aka powershell core available on all major platforms), and with somewhat limited functionality in powershell (aka windows powershell, windows-only, duh).

Just replace the /path/to/stack with your own value, e.g. via

PS> (Get-Command stack).Source

or

$ which stack

Another important note: this script will work for all haskell executables based on optparse-applicative! Simply replace the 'stack' with the name of your executable. On windows you might want to omit the extension for best behavior.

Also, to get tooltips, you would want to set Set-PSReadlineKeyHandler -Key Tab -Function MenuComplete in your powershell session or in your $PROFILE.