Feature: --granular-output flag

cabal2nix/cabal2nix.cabal

@@ -21,6 +21,8 @@ extra-source-files: README.md
                     CHANGELOG.md
                     test/golden-test-cases/*.cabal
                     test/golden-test-cases/*.nix.golden
+                    test/golden-test-cases-granular/*.cabal
+                    test/golden-test-cases-granular/*.nix.golden
 cabal-version:      1.24
 
 source-repository head
@@ -44,7 +46,9 @@ library
                       Distribution.Nixpkgs.Haskell.FromCabal.PostProcess
                       Distribution.Nixpkgs.Haskell.Hackage
                       Distribution.Nixpkgs.Haskell.OrphanInstances
+                      Distribution.Nixpkgs.Haskell.PackageNix
                       Distribution.Nixpkgs.Haskell.PackageSourceSpec
+                      Distribution.Nixpkgs.Haskell.TargetDerivations
                       Distribution.Nixpkgs.Haskell.Platform
   other-modules:      Paths_cabal2nix
   hs-source-dirs:     src

cabal2nix/hackage2nix/Main.hs

@@ -155,21 +155,24 @@ main = do
           attr :: String
           attr = if isInDefaultPackageSet then unPackageName name else mangle pkgId
 
-          drv :: Derivation
-          drv = fromGenericPackageDescription haskellResolver nixpkgsResolver targetPlatform (compilerInfo config) flagAssignment [] descr
-                  & src .~ urlDerivationSource ("mirror://hackage/" ++ display pkgId ++ ".tar.gz") tarballSHA256
-                  & editedCabalFile .~ cabalSHA256
-                  -- If a list of platforms is set in the hackage2nix configuration file, prefer that.
-                  -- Otherwise a list defined by PostProcess or Nothing is used.
-                  & metaSection.platforms %~ (Map.lookup name (supportedPlatforms config) <|>)
-                  & metaSection.badPlatforms %~ (Map.lookup name (unsupportedPlatforms config) <|>)
-                  & metaSection.hydraPlatforms %~ (if isHydraEnabled then id else const (Just Set.empty))
-                  & metaSection.broken ||~ isBroken
-                  & metaSection.maintainers .~ Map.findWithDefault Set.empty name globalPackageMaintainers
-                  & metaSection.homepage .~ ""
+          overrideDrv :: Derivation -> Derivation
+          overrideDrv drv' = drv'
+              & src .~ urlDerivationSource ("mirror://hackage/" ++ display pkgId ++ ".tar.gz") tarballSHA256
+              & editedCabalFile .~ cabalSHA256
+              -- If a list of platforms is set in the hackage2nix configuration file, prefer that.
+              -- Otherwise a list defined by PostProcess or Nothing is used.
+              & metaSection.platforms %~ (Map.lookup name (supportedPlatforms config) <|>)
+              & metaSection.badPlatforms %~ (Map.lookup name (unsupportedPlatforms config) <|>)
+              & metaSection.hydraPlatforms %~ (if isHydraEnabled then id else const (Just Set.empty))
+              & metaSection.broken ||~ isBroken
+              & metaSection.maintainers .~ Map.findWithDefault Set.empty name globalPackageMaintainers
+              & metaSection.homepage .~ ""
+
+          drv :: PackageNix
+          drv = fromGenericPackageDescription overrideDrv haskellResolver nixpkgsResolver targetPlatform (compilerInfo config) flagAssignment SingleDerivation [] descr
 
           overrides :: Doc
-          overrides = fcat $ punctuate space [ pPrint b <> semi | b <- Set.toList (view (dependencies . each) drv `Set.union` view extraFunctionArgs drv), not (isFromHackage b) ]
+          overrides = fcat $ punctuate space [ pPrint b <> semi | b <- Set.toList (view (allDependencies . each) drv `Set.union` view allExtraFunctionArgs drv), not (isFromHackage b) ]
       return $ render $ nest 2 $
         hang (doubleQuotes (text  attr) <+> equals <+> text "callPackage") 2 (parens (pPrint drv)) <+> (braces overrides <> semi)
 

cabal2nix/src/Cabal2nix.hs

@@ -60,6 +60,7 @@ data Options = Options
   , optHackageDb :: Maybe FilePath
   , optNixShellOutput :: Bool
   , optFlags :: [String]
+  , optOutputGranularity :: OutputGranularity
   , optCompiler :: CompilerId
   , optSystem :: Platform
   , optSubpath :: Maybe FilePath
@@ -111,6 +112,8 @@ options = do
     <- switch (long "shell" <> help "generate output suitable for nix-shell")
   optFlags
     <- many (strOption $ short 'f' <> long "flag" <> help "Cabal flag (may be specified multiple times)")
+  optOutputGranularity
+    <- flag SingleDerivation PerTarget $ long "granular-output" <> help "Generate an attrset with a derivation for each build target"
   optCompiler
     <- option parseCabal (long "compiler" <> help "compiler to use when evaluating the Cabal file" <> value buildCompilerId <> showDefaultWith prettyShow)
   optSystem
@@ -173,7 +176,7 @@ hpackOverrides :: Derivation -> Derivation
 hpackOverrides = over phaseOverrides (++ "prePatch = \"hpack\";")
                . set (libraryDepends . tool . contains (PP.pkg "hpack")) True
 
-cabal2nix' :: Options -> IO (Either Doc Derivation)
+cabal2nix' :: Options -> IO (Either Doc PackageNix)
 cabal2nix' opts@Options{..} = do
   pkg <- getPackage optHpack optFetchSubmodules optHackageDb optHackageSnapshot $
          Source {
@@ -186,7 +189,7 @@ cabal2nix' opts@Options{..} = do
          }
   processPackage opts pkg
 
-cabal2nixWithDB :: DB.HackageDB -> Options -> IO (Either Doc Derivation)
+cabal2nixWithDB :: DB.HackageDB -> Options -> IO (Either Doc PackageNix)
 cabal2nixWithDB db opts@Options{..} = do
   when (isJust optHackageDb) $ hPutStrLn stderr "WARN: HackageDB provided directly; ignoring --hackage-db"
   when (isJust optHackageSnapshot) $ hPutStrLn stderr "WARN: HackageDB provided directly; ignoring --hackage-snapshot"
@@ -201,7 +204,7 @@ cabal2nixWithDB db opts@Options{..} = do
          }
   processPackage opts pkg
 
-processPackage :: Options -> Package -> IO (Either Doc Derivation)
+processPackage :: Options -> Package -> IO (Either Doc PackageNix)
 processPackage Options{..} pkg = do
   let
       withHpackOverrides :: Derivation -> Derivation
@@ -210,26 +213,31 @@ processPackage Options{..} pkg = do
       flags :: FlagAssignment
       flags = configureCabalFlags (packageId (pkgCabal pkg)) `mappend` readFlagList optFlags
 
-      deriv :: Derivation
-      deriv = withHpackOverrides $ fromGenericPackageDescription (const True)
-                                            optNixpkgsIdentifier
-                                            optSystem
-                                            (unknownCompilerInfo optCompiler NoAbiTag)
-                                            flags
-                                            []
-                                            (pkgCabal pkg)
-              & src .~ pkgSource pkg
-              & subpath .~ fromMaybe "." optSubpath
-              & runHaddock %~ (optHaddock &&)
-              & jailbreak .~ optJailbreak
-              & hyperlinkSource .~ optHyperlinkSource
-              & enableLibraryProfiling .~ (fromMaybe False optEnableProfiling || optEnableLibraryProfiling)
-              & enableExecutableProfiling .~ (fromMaybe False optEnableProfiling || optEnableExecutableProfiling)
-              & metaSection.maintainers .~ Set.fromList (map (review ident) optMaintainer)
---            & metaSection.platforms .~ Set.fromList optPlatform
-              & doCheck &&~ optDoCheck
-              & doBenchmark ||~ optDoBenchmark
-              & extraFunctionArgs %~ Set.union (Set.fromList ("inherit lib":map (fromString . ("inherit " ++)) optExtraArgs))
+      overrideDrv :: Derivation -> Derivation
+      overrideDrv drv = withHpackOverrides $ drv
+        & src .~ pkgSource pkg
+        & subpath .~ fromMaybe "." optSubpath
+        & runHaddock %~ (optHaddock &&)
+        & jailbreak .~ optJailbreak
+        & hyperlinkSource .~ optHyperlinkSource
+        & enableLibraryProfiling .~ (fromMaybe False optEnableProfiling || optEnableLibraryProfiling)
+        & enableExecutableProfiling .~ (fromMaybe False optEnableProfiling || optEnableExecutableProfiling)
+        & metaSection.maintainers .~ Set.fromList (map (review ident) optMaintainer)
+  --            & metaSection.platforms .~ Set.fromList optPlatform
+        & doCheck &&~ optDoCheck
+        & doBenchmark ||~ optDoBenchmark
+        & extraFunctionArgs %~ Set.union (Set.fromList ("inherit lib":map (fromString . ("inherit " ++)) optExtraArgs))
+
+      deriv :: PackageNix
+      deriv = fromGenericPackageDescription overrideDrv
+                  (const True)
+                  optNixpkgsIdentifier
+                  optSystem
+                  (unknownCompilerInfo optCompiler NoAbiTag)
+                  flags
+                  optOutputGranularity
+                  []
+                  (pkgCabal pkg)
 
       shell :: Doc
       shell = vcat

cabal2nix/src/Distribution/Nixpkgs/Haskell.hs

@@ -1,8 +1,12 @@
 module Distribution.Nixpkgs.Haskell
   ( module Distribution.Nixpkgs.Haskell.BuildInfo
   , module Distribution.Nixpkgs.Haskell.Derivation
+  , module Distribution.Nixpkgs.Haskell.TargetDerivations
+  , module Distribution.Nixpkgs.Haskell.PackageNix
   )
   where
 
 import Distribution.Nixpkgs.Haskell.BuildInfo
 import Distribution.Nixpkgs.Haskell.Derivation
+import Distribution.Nixpkgs.Haskell.TargetDerivations
+import Distribution.Nixpkgs.Haskell.PackageNix

cabal2nix/src/Distribution/Nixpkgs/Haskell/ComponentDerivations.hs

@@ -0,0 +1,32 @@
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
+
+module Distribution.Nixpkgs.Haskell.ComponentDerivations
+  ( ComponentDerivations, libraries, executables, testExecutables, benchExecutables, nullComponentDerivations )
+  where
+
+import Prelude hiding ((<>))
+
+import Control.DeepSeq
+import Control.Lens
+import Data.List ( isPrefixOf )
+import Data.Map ( Map )
+import qualified Data.Map as Map
+import Data.Set ( Set )
+import qualified Data.Set as Set
+import Data.Set.Lens
+import Distribution.Nixpkgs.Fetch
+import Distribution.Nixpkgs.Haskell.BuildInfo
+import Distribution.Nixpkgs.Haskell.Derivation
+import Distribution.Nixpkgs.Haskell.OrphanInstances ( )
+import Distribution.Nixpkgs.Meta
+import Distribution.Package
+import Distribution.PackageDescription ( FlagAssignment, unFlagName, unFlagAssignment )
+import GHC.Generics ( Generic )
+import Language.Nix
+import Language.Nix.PrettyPrinting
+
+-- | A represtation of Nix expressions for building Haskell packages with component granularity.
+

cabal2nix/src/Distribution/Nixpkgs/Haskell/Derivation.hs

@@ -4,11 +4,14 @@
 {-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
 
 module Distribution.Nixpkgs.Haskell.Derivation
-  ( Derivation, nullDerivation, pkgid, revision, src, subpath, isLibrary, isExecutable
+  ( Derivation, SingleDerivation
+  , singleDerivation, nullSingleDerivation
+  , nullDerivation, pkgid, revision, src, subpath, isLibrary, isExecutable
   , extraFunctionArgs, libraryDepends, executableDepends, testDepends, configureFlags
-  , cabalFlags, runHaddock, jailbreak, doCheck, doBenchmark, testTarget, hyperlinkSource, enableSplitObjs
-  , enableLibraryProfiling, enableExecutableProfiling, phaseOverrides, editedCabalFile, metaSection
-  , dependencies, setupDepends, benchmarkDepends, enableSeparateDataOutput, extraAttributes
+  , cabalFlags, runHaddock, jailbreak, doCheck, doBenchmark, buildTarget, testTarget, hyperlinkSource
+  , enableSplitObjs , enableLibraryProfiling, enableExecutableProfiling, phaseOverrides
+  , editedCabalFile, metaSection , dependencies, setupDepends, benchmarkDepends, enableSeparateDataOutput
+  , extraAttributes, inputs
   )
   where
 
@@ -56,6 +59,7 @@ data Derivation = MkDerivation
   , _jailbreak                  :: Bool
   , _doCheck                    :: Bool
   , _doBenchmark                :: Bool
+  , _buildTarget                :: String
   , _testTarget                 :: String
   , _hyperlinkSource            :: Bool
   , _enableLibraryProfiling     :: Bool
@@ -79,16 +83,17 @@ nullDerivation = MkDerivation
   , _extraFunctionArgs = error "undefined Derivation.extraFunctionArgs"
   , _extraAttributes = error "undefined Derivation.extraAttributes"
   , _setupDepends = error "undefined Derivation.setupDepends"
-  , _libraryDepends = error "undefined Derivation.libraryDepends"
-  , _executableDepends = error "undefined Derivation.executableDepends"
-  , _testDepends = error "undefined Derivation.testDepends"
-  , _benchmarkDepends = error "undefined Derivation.benchmarkDepends"
+  , _libraryDepends = mempty
+  , _executableDepends = mempty
+  , _testDepends = mempty
+  , _benchmarkDepends = mempty
   , _configureFlags = error "undefined Derivation.configureFlags"
   , _cabalFlags = error "undefined Derivation.cabalFlags"
   , _runHaddock = error "undefined Derivation.runHaddock"
   , _jailbreak = error "undefined Derivation.jailbreak"
   , _doCheck = error "undefined Derivation.doCheck"
   , _doBenchmark = error "undefined Derivation.doBenchmark"
+  , _buildTarget = error "undefined Derivation.buildTarget"
   , _testTarget = error "undefined Derivation.testTarget"
   , _hyperlinkSource = error "undefined Derivation.hyperlinkSource"
   , _enableLibraryProfiling = error "undefined Derivation.enableLibraryProfiling"
@@ -110,7 +115,7 @@ instance Package Derivation where
 instance NFData Derivation
 
 instance Pretty Derivation where
-  pPrint drv@MkDerivation {..} = funargs (map text ("mkDerivation" : toAscList inputs)) $$ vcat
+  pPrint MkDerivation {..} = vcat
     [ text "mkDerivation" <+> lbrace
     , nest 2 $ vcat
       [ attr "pname"   $ doubleQuotes $ pPrint (packageName _pkgid)
@@ -135,6 +140,7 @@ instance Pretty Derivation where
       , boolattr "jailbreak" _jailbreak _jailbreak
       , boolattr "doCheck" (not _doCheck) _doCheck
       , boolattr "doBenchmark" _doBenchmark _doBenchmark
+      , onlyIf (not (null _buildTarget)) $ attr "buildTarget" $ string _buildTarget
       , onlyIf (not (null _testTarget)) $ attr "testTarget" $ string _testTarget
       , boolattr "hyperlinkSource" (not _hyperlinkSource) _hyperlinkSource
       , onlyIf (not (null _phaseOverrides)) $ vcat ((map text . lines) _phaseOverrides)
@@ -144,16 +150,35 @@ instance Pretty Derivation where
     , rbrace
     ]
     where
-      inputs :: Set String
-      inputs = Set.unions [ Set.map (view (localName . ident)) _extraFunctionArgs
-                          , setOf (dependencies . each . folded . localName . ident) drv
-                          , case derivKind _src of
-                              Nothing -> mempty
-                              Just derivKind' -> Set.fromList [derivKindFunction derivKind' | not isHackagePackage]
-                          ]
-
       renderedFlags = [ text "-f" <> (if enable then empty else char '-') <> text (unFlagName f) | (f, enable) <- unFlagAssignment _cabalFlags ]
                       ++ map text (toAscList _configureFlags)
-      isHackagePackage = "mirror://hackage/" `isPrefixOf` derivUrl _src
 
       postUnpack = string $ "sourceRoot+=/" ++ _subpath ++ "; echo source root reset to $sourceRoot"
+
+inputs :: Derivation -> Set String
+inputs drv@MkDerivation {..} = Set.unions 
+  [ Set.map (view (localName . ident)) _extraFunctionArgs
+  , setOf (dependencies . each . folded . localName . ident) drv
+  , case derivKind _src of
+      Nothing -> mempty
+      Just derivKind' -> Set.fromList [derivKindFunction derivKind' | not isHackagePackage]
+  ]
+  where
+    isHackagePackage = "mirror://hackage/" `isPrefixOf` derivUrl _src
+
+newtype SingleDerivation = SingleDerivation 
+  { _singleDerivation :: Derivation }
+  deriving (Show, Generic)
+
+makeLenses ''SingleDerivation
+
+nullSingleDerivation :: SingleDerivation
+nullSingleDerivation = SingleDerivation
+  { _singleDerivation = error "undefined SingleDerivation.derivation"
+  }
+
+instance NFData SingleDerivation
+
+instance Pretty SingleDerivation where
+  pPrint SingleDerivation {..} = funargs (map text ("mkDerivation" : toAscList (inputs _singleDerivation))) $$ 
+    pPrint _singleDerivation