bracketcall.hs

          bracket
            (do
                sock <- socket AF_UNIX Stream 0
                setSocketOption sock ReuseAddr 1
                bind sock $ SockAddrUnix s
                listen sock maxListenQueue
                return sock
            )
            (\sock -> do
                sockhandle <- socketToHandle sock ReadWriteMode
                hClose sockhandle
            )
            (\sock -> Network.Wai.Handler.Warp.runSettingsSocket warpsettings sock app)

out.log

[nix-shell:~/git/hub/hledger]$ stack exec -- hledger-web --socket /tmp/foo.sock
Stack has not been tested with GHC versions above 8.6, and using 8.8.1, this may fail
Stack has not been tested with Cabal versions above 2.4, but version 3.0.0.0 was found, this may fail
09/Jan/2020:16:27:16 +0100 [Info#yesod-core] Application launched @(yesod-core-1.6.17-8khiymix0izHkaDEW7detY:Yesod.Core.Dispatch src/Yesod/Core/Dispatch.hs:163:11)
Serving web UI and API on 127.0.0.1:5000 with base url http://127.0.0.1:5000
Press ctrl-c to quit
^C

[nix-shell:~/git/hub/hledger]$ stack exec -- hledger-web --socket /tmp/foo.sock
Stack has not been tested with GHC versions above 8.6, and using 8.8.1, this may fail
Stack has not been tested with Cabal versions above 2.4, but version 3.0.0.0 was found, this may fail
09/Jan/2020:16:27:25 +0100 [Info#yesod-core] Application launched @(yesod-core-1.6.17-8khiymix0izHkaDEW7detY:Yesod.Core.Dispatch src/Yesod/Core/Dispatch.hs:163:11)
Serving web UI and API on 127.0.0.1:5000 with base url http://127.0.0.1:5000
Press ctrl-c to quit
hledger-web: Network.Socket.bind: resource busy (Address already in use)