demo srid/haskell-flake#212 (comment)

baz.cabal

@@ -0,0 +1,23 @@
+cabal-version:   3.0
+name:            bar
+version:         0.1.0.0
+license:         MIT
+license-file:    LICENSE
+author:          Sridhar Ratnakumar
+maintainer:      [email protected]
+category:        Other
+build-type:      Simple
+extra-doc-files: CHANGELOG.md
+
+common warnings
+    ghc-options: -Wall
+
+executable bar
+    import:           warnings
+    main-is:          Main.hs
+    build-depends:
+        base
+      , foo
+      , text
+    hs-source-dirs:   src
+    default-language: Haskell2010

cabal.project

@@ -1,6 +1,7 @@
 packages:
     ./foo
     ./bar
+    ./
 
 source-repository-package
   type: git

flake.nix

@@ -25,7 +25,7 @@
         # packages = {
         #   halogen-chess.source = inputs.halogen-chess;
         # };
-        packages.default = self'.packages.bar;
+        packages.default = self'.packages.baz;
       };
     };
 }

src/Main.hs

@@ -0,0 +1,10 @@
+module Main where
+
+import Foo (fooFunc)
+
+import Data.Text
+
+main :: IO ()
+main = do
+  putStrLn "Hello, Haskell!"
+  fooFunc