We need a diagnostic tool

[tomjaguarpaw]

We need some sort of diagnostic tool that users can run to minimally verify that their Haskell setup is working as expected. We can't handle support requests like "libgmp.so: cannot open shared object file" on a disparate network of forums like Reddit.

The diagnostic tool could say something like

User was running
* cabal version 3.X
* ghc version 9.Y
* obtained by ghcup version Z
* architecture NetLinuxOS i286
* operating system DebHat Harried Maintainer 6.66

* Can compile and link simple program with ghc: Yes
* Can compile and link simple program with stack: Yes
* Can compile and link simple program with cabal: No
     Cabal is available at
         * ~/.cabal/bin/cabal
         * ~/.ghcup/bin/cabal
     but none of these are on PATH

or

...
* Can compile and link simple program with ghc: No
    Got error: "libgmp.so: cannot open shared object file"
    This is a Debian system and libgmp-dev is not installed.
    To fix please issue: apt install libgmp-dev

See also

• can't install QuickCheck haskell/cabal#7892 (comment)
• https://www.reddit.com/r/haskell/comments/ry2cc4/unexpected_usage_error_libgmpso_cannot_open/

[googleson78]

haskell-language-servers --probe-tools gives some minimal info in this spirit:

blademaster :: ~ » haskell-language-server-wrapper --probe-tools
haskell-language-server version: 1.5.1.0 (GHC: 8.10.7) (PATH: /home/googleson78/.ghcup/bin/haskell-language-server-wrapper-1.5.1) (GIT hash: 745ef26f406dbdd5e4a538585f8519af9f1ccb09)
Tool versions found on the $PATH
cabal:          3.6.2.0
stack:          2.7.3
ghc:            8.10.7