Get version of used library with Stack

Question

I have a Haskell project that's built with Stack.

In my Cabal file, I've added a bunch of libraries as dependencies, tls for example.

Is there a command to get the version of a specific library used in my project?

I know from stack.yaml that I'm using the resolver lts-14.16. I could therefore visit the page of this LTS on Stackage and look for the version number of my library there. But I hope there's a more straightforward way, using the command line, to do this.

Answer 1

stack ls dependencies

This command lists the dependencies and their versions of the current project, as mentioned here. It produces output like the following:

StateVar 1.2
aeson 1.4.6.0
ansi-terminal 0.9.1
array 0.5.3.0
asn1-encoding 0.9.6
asn1-parse 0.9.5
asn1-types 0.3.3
async 2.2.2
attoparsec 0.13.2.3
base 4.12.0.0

Use grep to pick the library you're interested in:

stack ls dependencies 2>/dev/null | grep "^tls"

We use 2>/dev/null to silence any warnings that Stack might produce regarding the project.

If you want to go further and visualize your dependencies, as a graph or tree for instance, use stack dot.