Re: [xmonad] workspaces conditional on host name

20 Sep 2022


      Using environment variables to get hostname feels a bit unstable. I personally read /etc/hostname to determine the hostname, like this:

hostname <- fmap trimString (readFile "/etc/hostname")

where `trimString` is:

trimString :: String -> String
trimString = f . f
   where f = reverse . dropWhile isSpace

There's also `hostname` package, which uses proper library functions to determine hostname: https://hackage.haskell.org/package/hostname

--
Best regards,
Platon Pronko
PGP 2A62D77A7A2CB94E

On 2022-09-19 23:05, Brandon Allbery wrote:
...
You might check if `$HOSTNAME` is actually exported. There's a
difference between "exported" and merely "set" in most shells; use the
"export" command (or "env") to see which names are actually exported.
(On my Ubuntu system, `$HOSTNAME` isn't set at all.)
On Mon, Sep 19, 2022 at 3:41 PM Ramon Diaz-Uriarte  wrote:
...
Dear Brandon and Platon,
Thanks a lot! I fixed it as suggested (use a new, different, variable name to hold the value from the let, and pass that to myConfig), and it now works. :-)
Actually, there was something else that was not working: when I print
io (getEnv "HOSTNAME")
and
io (getEnv "HOST")
I get Nothing in both cases. I do not understand why that happens, since
ramon@Phelsuma:~$ hostname
Phelsuma
ramon@Phelsuma:~$ echo $HOSTNAME
Phelsuma
Anyway, I solved it by setting in ~/.profile
export HOSTNAME_PROFILE_XMONAD=$HOSTNAME
And doing, in xmonad.hs
hostname <- io (getEnv "HOSTNAME_PROFILE_XMONAD")
Maybe it is related to how I call XMonad (it is called from /usr/bin/xmonad-session, which if I remember correctly I started doing because I use lxdm as display manager).
Thanks again.
Best,
R.
On Mon, 19-September-2022, at 19:33:08, Brandon Allbery  wrote:
...
Oh, I missed that. Yes, the `myWorkspaces` you set in `main` has
nothing to do with the global one which `myConfig` sees; you need to
pass the new one in. And possibly rename it so it's more obvious that
they're not related.
On Mon, Sep 19, 2022 at 1:30 PM Platon Pronko  wrote:
...
Hi!
It looks like `myWorkspaces` in `myConfig` definition is referencing this defintion:
myWorkspaces    = map show[1..7]
instead of the one you actually want. Maybe try adding workspaces as an argument to `myConfig`? Something like this:
myConfig workspaces = def {
           --- blablabla
           workspaces = workspaces
           }
main :: IO ()
main = do
     hostname <- io (getEnv "HOSTNAME")
     let workspaces = case hostname of
           Just "Phelsuma" -> myWorkspacesPhelsuma
           Just "Triturus" -> myWorkspacesTriturus
           _ -> myWorkspaces
     xmonad
        $ ewmh
        $ dynamicProjects myProjects
        $ withNavigation2DConfig def
        $ docks
        $ withEasySB (statusBarProp "xmobar ~/.xmonad/.xmobarrc" (pure myXmobarPP)) defToggleStrutsKey
        $ myConfig workspaces
--
Best regards,
Platon Pronko
PGP 2A62D77A7A2CB94E
On 2022-09-19 19:01, Ramon Diaz-Uriarte wrote:
...
Dear All,
I use XMonad on different machines. The configuration is identical, except for the default workspaces, so I'd like to have the config file set the default workspaces automagically. Haskell ignorant here, but googling around I think I am almost there. These are, I think, the relevant pieces
myWorkspaces    = map show[1..7]
myWorkspacesPhelsuma    = map show[1..3] ++ ["top", "sync", "zot",  "whats"]
myWorkspacesTriturus    = map show[1..2] ++ ["top", "sync"]
main :: IO ()
main = do
     hostname <- io (getEnv "HOSTNAME")
     let myWorkspaces = case hostname of
           "Phelsuma" -> myWorkspacesPhelsuma
           "Triturus" -> myWorkspacesTriturus
           _ -> myWorkspaces
     xmonad
        $ ewmh
        $ dynamicProjects myProjects
        $ withNavigation2DConfig def
        $ docks
        $ withEasySB (statusBarProp "xmobar ~/.xmonad/.xmobarrc" (pure myXmobarPP)) defToggleStrutsKey
        $ myConfig
myConfig = def {
           --- blablabla
           workspaces =  myWorkspaces
           }
However, I keep getting an error:
• Couldn't match expected type ‘Maybe String’
                    with actual type ‘[Char]’
      • In the pattern: "Phelsuma"
        In a case alternative: "Phelsuma" -> myWorkspacesPhelsuma
        In the expression:
          case hostname of
            "Phelsuma" -> myWorkspacesPhelsuma
            "Triturus" -> myWorkspacesTriturus
            _ -> myWorkspaces
      |
882 |          "Phelsuma" -> myWorkspacesPhelsuma
      |          ^^^^^^^^^^
(and the same error for the second entry, "Triturus")
This I think should be fairly easy to fix, but I can't find how. I tried writing the case section as
let myWorkspaces = case hostname of
           Just "Phelsuma" -> myWorkspacesPhelsuma
           Just "Triturus" -> myWorkspacesTriturus
           _ -> myWorkspaces
and that does not give me an error, but it seems to ignore the actual
hostname and uses the "default" one (the one with workspaces 1 to 7). So I
think I am using "Just" incorrectly and possibly also misunderstanding how
"let" works in main.
Any suggestions?
Thanks,
_______________________________________________
xmonad mailing list
xmonad@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/xmonad
--
Ramon Diaz-Uriarte
Department of Biochemistry, Lab B-31
Facultad de Medicina
Universidad Autónoma de Madrid
Arzobispo Morcillo, 4
28029 Madrid
Spain
Phone: +34-91-497-2412
Email: rdiaz02@gmail.com
        r.diaz@uam.es
https://ligarto.org/rdiaz