Enable support for library build

script/test

@@ -3,6 +3,7 @@
 #!nix-shell -I nixpkgs=./nix
 #!nix-shell -p snack-exe
 #!nix-shell -p shfmt
+#!nix-shell -p jq
 #!nix-shell --pure
 # vim: ft=sh sw=2 et
 
@@ -74,6 +75,11 @@ pushd tests/library
 ./test
 popd
 
+banner "Test library-2"
+pushd tests/library-2
+./test
+popd
+
 banner "Test stack-exe formatting"
 list=$(shfmt -i 2 -l bin/snack)
 if [[ -n "$list" ]]; then

snack-lib/default.nix

@@ -7,6 +7,7 @@
 , stdenv
 , symlinkJoin
 , writeScript
+, writeText
 , runCommand
 , callPackage
 }:
@@ -104,6 +105,8 @@ let
         "${buildModule ghcWith mainModSpec}/Main.o";}
       mainModSpec.moduleImports;
 
+  # returns a attrset where the keys are the module names and the values are
+  # the modules' object file path
   buildLibrary = ghcWith: modSpecs:
       buildModulesRec ghcWith {} modSpecs;
 
@@ -148,8 +151,9 @@ let
   # module spec
   ghciWithMain = ghcWith: mainModSpec:
     let
-      ghcOpts = allTransitiveGhcOpts [mainModSpec];
-      ghc = ghcWith (allTransitiveDeps [mainModSpec]);
+      modSpecs = [mainModSpec];
+      ghcOpts = allTransitiveGhcOpts modSpecs;
+      ghc = ghcWith (allTransitiveDeps modSpecs);
       ghciArgs = lib.strings.escapeShellArgs
         (ghcOpts ++ absoluteModuleFiles);
       absoluteModuleFiles =
@@ -221,6 +225,7 @@ let
             ghcOptsByModuleName = ghcOptsByModuleName;
           };
 
+  # TODO: "executable" is a bad name
   executable = pkgDescr:
     let
       moduleSpecFold' = modSpecFoldFromPackageSpec topPkgSpec;
@@ -230,7 +235,19 @@ let
       mainModName = topPkgSpec.packageMain;
     in
       if builtins.isNull topPkgSpec.packageMain
-      then abort "Snack does not support building libraries!"
+      then
+        let
+          modNames = listModulesInDir topPkgSpec.packageBase;
+          fld = moduleSpecFold' modSpecs;
+          modSpecs = foldDAG fld modNames;
+        in
+          {
+            build =
+              writeText
+                "library-build"
+                (builtins.toJSON (buildLibrary ghcWith (builtins.attrValues modSpecs)));
+            ghci =  abort "No GHCi support for libraries!";
+          }
       else
         let
           mainModName = topPkgSpec.packageMain;
@@ -240,10 +257,9 @@ let
               modSpecs = foldDAG fld [mainModName];
             in modSpecs.${mainModName};
         in
-
-        { build = linkMainModule ghcWith mainModSpec;
-          ghci = ghciWithMain ghcWith mainModSpec;
-        };
+          { build = linkMainModule ghcWith mainModSpec;
+            ghci = ghciWithMain ghcWith mainModSpec;
+          };
 in
   {
     inherit

tests/library-2/golden

@@ -0,0 +1,5 @@
+1
+2
+3
+4
+5

tests/library-2/golden.jq

@@ -0,0 +1,5 @@
+[
+  "Bar",
+  "Foo",
+  "FooBar"
+]

tests/library-2/lib/Bar.hs

@@ -0,0 +1,7 @@
+module Bar where
+
+import Conduit
+import FooBar
+
+main :: IO ()
+main = runConduit $ spitOut .| takeC 5 .| digest

tests/library-2/lib/Foo.hs

@@ -0,0 +1,6 @@
+module Foo where
+
+import qualified Bar
+
+someFunc :: IO ()
+someFunc = Bar.main

tests/library-2/snack.nix

@@ -0,0 +1,10 @@
+let
+  my-lib =
+    { src = ./src;
+      dependencies = [ "conduit" ];
+    };
+in
+  { src = ./lib;
+    dependencies = [ "conduit" ];
+    packages = [ my-lib ];
+  }

tests/library-2/src/FooBar.hs

@@ -0,0 +1,9 @@
+module FooBar where
+
+import Conduit
+
+spitOut :: ConduitT () Int IO ()
+spitOut = yieldMany [ 1 ..]
+
+digest :: ConduitT Int Void IO ()
+digest = mapM_C print

tests/library-2/test

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# vim: ft=sh sw=2 et
+
+set -euo pipefail
+
+TMP_FILE=$(mktemp)
+
+cat $($SNACK build) | jq -M 'keys' > $TMP_FILE
+
+diff golden.jq $TMP_FILE
+
+# TODO: enable this once supported
+#capture_io "$TMP_FILE" someFunc | $SNACK ghci
+#diff golden $TMP_FILE
+
+rm $TMP_FILE