Add module dependencies

script/test

@@ -14,3 +14,7 @@ popd
 pushd tests/nested
 snack build
 popd
+
+pushd tests/dependencies
+snack build
+popd

snack/default.nix

@@ -53,6 +53,22 @@ let
 
   singleOutModule = base: mod: singleOut base (moduleToFile mod);
 
+  singleOutModulePath = base: mod:
+    "${singleOut base (moduleToFile mod)}/${moduleToFile mod}";
+
+  makeModuleSpecRec = base:
+    pkgs.lib.fix
+      (f: isMain: modName:
+        makeModuleSpec
+          modName
+          (map (f false) (listModuleDependencies base modName))
+          isMain
+      ) true;
+
+  buildFrom = base: modName: linkModuleObjects base
+    (makeModuleSpecRec base modName);
+
+
   buildModule = base: mod:
     let
       objectName = mod.moduleName;
@@ -92,6 +108,36 @@ let
       ];
     };
 
+  # Generate a list of haskell module names needed by the haskell file
+  listModuleDependencies = base: modName:
+    builtins.fromJSON
+    (builtins.readFile (listModuleDependenciesJSON base modName));
+
+  listModuleDependenciesJSON = base: modName:
+    pkgs.stdenv.mkDerivation
+      { name = "module-deps";
+        src = null;
+        builder = pkgs.writeScript "dependencies-json"
+        ''
+          echo "preparing dependencies"
+          source $stdenv/setup
+          # Poor man's module parser
+          FILTER=$(cat <<'EOF'
+          s/import\s*\(qualified\|\)\s*\(\S*\)\s*\(.*\)/\2/p;
+          EOF
+          )
+          JSON=$(cat <<'EOF'
+          s/\(.*\)/"\1"/;
+          $!s/$/,/;
+          EOF
+          )
+          sed -n "$FILTER" ${singleOutModulePath base modName} \
+            | (echo "["; sed "$JSON"; echo "]") > $out
+          echo "done:preparing dependencies"
+          cat $out
+        '';
+      };
+
   # Returns an attribute set where the keys are the module names and the values
   # are the '.o's
   flattenModuleObjects = base: mod':
@@ -139,5 +185,10 @@ let
   ## TODO: use ghc -M for module dependencies
 in
   {
-    inherit linkModuleObjects makeModuleSpec;
+    inherit
+    buildFrom
+    linkModuleObjects
+    listModuleDependenciesJSON
+    makeModuleSpec
+    ;
   }

tests/dependencies/snack.nix

@@ -0,0 +1,3 @@
+# This "snack" passing is ugly, figure out a nice way of passing snack-lib
+with (import ../../nix {}).snack-lib;
+buildFrom ./src "Foo"

tests/dependencies/src/BarFoo.hs

@@ -0,0 +1,3 @@
+module BarFoo where
+
+barFoo = "bar foo"

tests/dependencies/src/Data/Foo.hs

@@ -0,0 +1,2 @@
+module Data.Foo where
+dataFoo = "Data, Foo."

tests/dependencies/src/Foo.hs

@@ -0,0 +1,10 @@
+import Data.Foo
+import Haskell
+import  qualified  FooBar
+import  qualified  BarFoo as F
+
+main = do
+  putStrLn dataFoo
+  putStrLn haskell
+  putStrLn FooBar.fooBar
+  putStrLn F.barFoo

tests/dependencies/src/FooBar.hs

@@ -0,0 +1,2 @@
+module FooBar where
+fooBar = "foo bar"

tests/dependencies/src/Haskell.hs

@@ -0,0 +1,2 @@
+module Haskell where
+haskell = "haskell!"