Re: [Haskell-cafe] Cabal install fails, don't understand why

30 Mar 2024

      Am Freitag, dem 29.03.2024 um 13:48 -0400 schrieb Brandon Allbery:
...
On Fri, Mar 29, 2024 at 1:15 PM Volker Wysk  wrote:
...
...
The proper way to work with libraries outside of a project is "cabal
repl"
or "stack ghci" as appropriate. For quick one-offs with cabal, you can
use
e.g. `cabal repl -b HsShellScript`. (I don't know the stack
equivalent,
sorry.)
What do you mean by "libraries outside of a project"? The library is one
project by itself. I don't (?) have any libraries outside of projects
(that
I know of).
Cabal and stack are designed around the notion of projects, defined by a
cabal file (or `package.yaml` if you use Hpack), `stack.yaml` for stack,
optional `cabal.project` for cabal. Projects are sandboxed such that the
package(s) in the project use consistent versions of all dependencies.
Neither tool handles use outside of a project well, although stack has a
global configuration (whose use for this is deprecated iirc) and cabal
uses ghc's environment files when requested. So something that isn't
really intended for use as part of a project isn't well handled by either
one.
Sounds complicated. I guess the best way to avoid trouble, is to do
everything in projects and avoid code outside of projects.

...
The biggest problem with both stack's global configuration and cabal's use
of environment files is the need for manual management when new versions
of packages are released: neither tool currently gives you any way to
manage either, and having multiple versions of a package in either invites
trouble. I can't speak for stack, but cabal devs are aware of the problem
and considering how best to deal with it (see for
example https://github.com/haskell/cabal/issues/9581).
You mean when you have code outside of projects, I guess. Multiple versions
should be easily managed by cabal (or stack, which I don't know).

I'm willing to subject myself to the way to do it, which is predefined by
cabal (or stack), when in return, it all works without much hassle. I want
to write code, not fight with the package management system.

Happy hacking,
Volker