I would love to be able to use chicken on a regular basis, but unfortunately it is an enormous pain to get it install on a system at the same time as mono because the mono c# compiler and the chicken scheme compiler have the same name [0].
nix-shell -p chicken --run csi
or alternatively, tweak the package to rename them:
chicken = pkgs.chicken.overrideAttrs (attrs: {
postInstall = attrs.postInstall + "\n" + "mv $out/bin/{csi,chicken-csi}
})