stack ghci probably shouldn't change the code page

[ndmitchell]

On Windows, if I run stack ghci, when I get errors I see:

<interactive>:2:53:
    Not in scope: ‘main’
    Perhaps you meant ‘min’ (imported from Prelude)

If stack ghci on Windows is changing the codepage to something the console very definitely doesn't support, and as a result, it looks terrible. Without stack in the way I get:

<interactive>:2:1:
    Not in scope: `main'

I would be entirely happy without any smart quotes, but garbling the text nearby is a little unfortunate.

[snoyberg]

Would you be able to take a crack at the codepage stuff? This is an area I have virtually no experience with, and I haven't been able to reproduce these problems since both consoles I've tried seem to support utf8 just fine

[ndmitchell]

I don't have much time at the moment. I'm only taking such an active interest in stack all of a sudden because cabal decided to eat itself at a bad time :). This is a minor annoyance, and one I can ignore reasonably easily.

I'm just on the standard Windows 8.1 cmd prompt. You change the codepage to call GHC to dump some information? Do you have an example somewhere of which thing goes wrong without changing the code page.

[snoyberg]

Using the standard cmd on Windows 10:

It's theoretically possible that this is because I've installed Hebrew support, but I really have no idea why my cmd prompt works in this case and yours doesn't. Regarding reproducing problems: https://ghc.haskell.org/trac/ghc/ticket/10762 gives some solid repros for the bugs we were encountering. Note that -ddump-hi is necessary in stack in order to detect files missing from the .cabal file.

[ndmitchell]

I'll be upgrading to Windows 10 when things calm down, so maybe its fixed there. If there is a Win 8.1 only bug it's a lot less important.

[ndmitchell]

BTW, why not use -M to generate a Makefile for the project? That seems much faster and easier than dumping all the hi files and will give you the same information.

[snoyberg]

It doesn't; the hi dump includes the TH dependencies, and is generated as part of the normal build process. I'd be surprised if generating the Makefile as a separate step is faster than that, plus we'd have to write a significantly more complicated parser.

[iharh]

Michael, which font do you use at the screenshot from Win-10?

[snoyberg]

Consolas

[iharh]

Thanx. Probably I need to upgrade to Win-10 at some point. At my current Win-7 Consolas looks really ugly.
BTW, are you using ClearType or some additional effects?

[snoyberg]

Shrug, no idea. I haven't tweaked things much.

On Thu, Aug 13, 2015, 9:12 AM Ihar Hancharenka notifications@github.com
wrote:

Thanx. Probably I need to upgrade to Win-10 at some point. At my current
Win-7 Consolas looks really ugly.
BTW, are you using ClearType or some additional effects?

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[iharh]

BTW, At my Win-8 laptop Consolas is also much nicer. A also haven't tweaked it at all :)

[3noch]

I've had hit-and-miss experiences with this code-page stuff. Windows 10 console seems to support it well enough, but Console2 (a popular console replacement) doesn't like it at all. I wonder if it would be best to offer some sort of local (and even global) setting to disable this feature.

[ndmitchell]

With Win10 I don't have any problems, the characters display properly, so my initial concern is no longer a problem.

[3noch]

I think Win10 will be a minority for a while still.

[ndmitchell]

Trying it again after a stack upgrade --git shows it doesn't work, so I may have been using a stale stack on the path when I reported the codepage didn't break it. Now, with vanilla Windows 10, stack ghci shows garbage characters.

[snoyberg]

I've just pushed a commit to master which does the following:

• Code page changing only applies to the build command
• Adds a command line parameter for controlling what happens with the code page

[ndmitchell]

Confirmed that fixes my issue with ghci.

[snoyberg]

Cool, closing.

[lukexi]

Using Cmder (http://cmder.net/) and MSYS2, I seem to need to pass the --no-modify-code-page option to get correct output. Is this something I can put in my global config.yaml?

[borsboom]

@lukexi Not currently. You might want to comment in #846 where we are planning to generally add many command-line arguments to the config file.

[lukexi]

Thanks Emanuel!