[Jackaudio] pkg-config not recognizing JACK2 on NixOS

Hi, I'd like to use JACK to send MIDI messages from a Haskell program I wrote[1] to a DAW. I downloaded the JACK library for Haskell[2]. When I try to open a REPL to interactively run some of the library's example code, some requirements fail to build, and `cabal` (a Haskell build tool) reports that `pkg-config` cannot find the an appropriate version of JACK: jeff@jbb-hp17:jack$ cabal repl Build profile: -w ghc-9.0.2 -O1 In order, the following will be built (use -v for more details): - jack-0.7.2 (lib) (first run) Configuring library for jack-0.7.2.. cabal: The pkg-config package 'jack' version >=0.118 && <1 || >=1.9.8 && <2 is required but it could not be found. But my version of JACK is well above 1.9.8 and well below 2: jeff@jbb-hp17:jack$ jackd --version jackdmp version 1.9.19 tmpdir /dev/shm protocol 9 It might matter that I'm running NixOS. I use JACK all the time, via QJackCtl. Many thanks, Jeff [1] https://github.com/JeffreyBenjaminBrown/montevideo [2] https://hackage.haskell.org/package/jack -- Jeff Brown | Jeffrey Benjamin Brown LinkedIn <https://www.linkedin.com/in/jeffreybenjaminbrown> | Github <https://github.com/jeffreybenjaminbrown> | Twitter <https://twitter.com/carelogic> | Facebook <https://www.facebook.com/mejeff.younotjeff>