Thanks. But alas I have no clue about whether I want a v1-install or a v2-install, nor how to achieve them if I knew what they were. I just want to install ‘hspec’ so that I can use it when compiling a program. How would I do that?

The instructions here https://wiki.haskell.org/Cabal-Install just say “cabal install hspec” which is what I tried. Those instructions are pointed to from here https://wiki.haskell.org/Cabal/How_to_install_a_Cabal_package, which in turn are pointed to from the main Cabal home page https://www.haskell.org/cabal/.

I must be missing something.

Simon

From: Brandon Allbery <allbery.b@gmail.com>
Sent: 15 April 2019 22:54
To: Simon Peyton Jones <simonpj@microsoft.com>
Cc: ghc-devs@haskell.org
Subject: Re: Cabal woes

I think you wanted v1-install to install a library into the user package database, since your cabal is 3.x and the v2-* commands are now the default (that is, you did what used to be cabal new-install or cabal v2-install).

On Mon, Apr 15, 2019 at 5:47 PM Simon Peyton Jones via ghc-devs <ghc-devs@haskell.org> wrote:

I’m trying to install ‘hspec’ on my WSL (Windows subsystem for Linux) system.

But I fail; see below.

For some reason cabal complains about installing a library. (That seems peculiar – isn’t that what cabal is for?) But it helpfully suggests adding –lib.

Alas, cabal then crashes outright, which should never happen.

So I’m stuck. What should I do?

Thanks

Simon

simonpj@MSRC-9870733:~$ cabal --version

cabal-install version 3.0.0.0

compiled using version 3.0.0.0 of the Cabal library

simonpj@MSRC-9870733:~$ cabal install hspec

Resolving dependencies...

Up to date

Warning: You asked to install executables, but there are no executables in

target: hspec. Perhaps you want to use --lib to install libraries instead.

simonpj@MSRC-9870733:~$ cabal install --lib hspec

Resolving dependencies...

Up to date

Distribution/Simple/GHC.hs:1959:5-56: Irrefutable pattern failed for pattern Just ghcPkgProg

simonpj@MSRC-9870733:~$ which ghc

/opt/ghc/bin/ghc

simonpj@MSRC-9870733:~$ which ghc-pkg

/opt/ghc/bin/ghc-pkg

simonpj@MSRC-9870733:~$

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