Terminal width detection isn't done on Windows

[kadoban]

The terminal width detection (that is used for pretty-printing log/warning/error output) is not done on Windows.

If anyone is interested in contributing that, it should be fairly trivial for the right person. It should go in windows/System/Terminal.hs and do something similar in function to what is done in unix/System/Terminal.hsc

[eye942]

@kadoban
Hi, is anyone working on this?

I would like to work on it and have a few ideas on where to start.

I'm pretty sure I understand unix/System/Terminal.hsc, but Windows doesn't seem to have that sort of convenience.

However, there are a couple ways that I think it can be implemented by increasing order of difficulty:

1. A Haskell Package called Win32. Haskell Platform says that it's a core package. This would be very simple, just an import and returning a simple function call.
2. Calling Powershell to use the command (Get-Host).UI.RawUI.WindowSize.Width and parsing the result, which is just an integer.
3. Calling mode and parsing the results, which is a pretty-printed table.
4. Using FFI to mess with the Windows API. This is not trivial.

Sincerely,
Eric

[mgsloan]

@eye942 Approach (1) seems good to me. I don't think anyone is working on this, feel free to have at it

[ndmitchell]

I recommend the terminal-size library which does this in a cross platform manner. It's used in ghcid with much success.

[snoyberg]

Fixed by #4797