nix: Add a tool for checking Haskell imports and exports (#1768)

.gitignore

@@ -21,4 +21,3 @@ __pycache__
 *.tix
 coverage
 .hpc
-imports.png

default.nix

@@ -124,9 +124,15 @@ rec {
   style =
     pkgs.callPackage nix/style.nix { };
 
+  # Tooling for analyzing Haskell imports and exports.
+  hsie =
+    pkgs.callPackage nix/hsie {
+      ghcWithPackages = pkgs.haskell.packages."${compiler}".ghcWithPackages;
+    };
+
   # Development tools, including linting and styling scripts.
   devtools =
-    pkgs.callPackage nix/devtools.nix { inherit tests style devCabalOptions; };
+    pkgs.callPackage nix/devtools.nix { inherit tests style devCabalOptions hsie; };
 
   # Scripts for publishing new releases.
   release =

nix/devtools.nix

@@ -4,6 +4,7 @@
 , devCabalOptions
 , entr
 , graphviz
+, hsie
 , silver-searcher
 , style
 , tests
@@ -98,40 +99,57 @@ let
         ${style}/bin/postgrest-style-check
       '';
 
-  importsgraph =
+  dumpMinimalImports =
     checkedShellScript
       {
-        name = "postgrest-importsgraph";
+        name = "postgrest-dump-minimal-imports";
-        docs =
+        docs = "Dump minimal imports into given directory.";
-          ''
-            Render the imports between PostgREST modules as a graph.
-
-            Output is written to 'imports.png' in the root directory of the project.
-          '';
         inRootDir = true;
       }
       ''
-        imports=$(
+        dumpdir="$1"
-          grep -rE 'import .*PostgREST\.' src main \
+        tmpdir="$(mktemp -d)"
-            | sed -E \
+        mkdir -p "$dumpdir"
-                -e 's|/|\.|g' \
+        ${cabal-install}/bin/cabal v2-build ${devCabalOptions} \
-                -e 's/(src|main)\.(.*)\.hs:import .*(PostgREST\.\S+)( .*)?/"\2" -> "\3"/'
+          --builddir="$tmpdir" \
-        )
+          --ghc-option=-ddump-minimal-imports \
+          --ghc-option=-dumpdir="$dumpdir" \
+          1>&2
+        rm -rf "$tmpdir"
 
-        labels=$(
+        # Fix OverloadedRecordFields imports
-          grep -rE '^(--)?\s*Description\s*:' src main \
+        # shellcheck disable=SC2016
-            | sed -E \
+        sed -E 's/\$sel:.*://g' -i "$dumpdir"/*
-                -e 's|/|\.|g' \
-                -e 's/^(src|main)\.(.*)\.hs:(--)?\s*Description\s*:\s*(.*)$/"\2" [label="\2\\n\4"]/'
-        )
-
-        cat <<EOF | ${graphviz}/bin/dot -Tpng > imports.png
-          digraph {
-            $imports
-            $labels
-          }
-        EOF
       '';
+
+  hsieMinimalImports =
+    checkedShellScript
+      {
+        name = "postgrest-hsie-minimal-imports";
+        docs = "Run hsie with a provided dump of minimal imports.";
+      }
+      ''
+        tmpdir="$(mktemp -d)"
+        ${dumpMinimalImports} "$tmpdir"
+        ${hsie} "$tmpdir" "$@"
+        rm -rf "$tmpdir"
+      '';
+
+  hsieGraphModules =
+    checkedShellScript
+      {
+        name = "postgrest-hsie-graph-modules";
+        docs = "Create a PNG graph of modules imported within the codebase.";
+      }
+      ''${hsie} graph-modules main src | ${graphviz}/bin/dot -Tpng -o "$1"'';
+
+  hsieGraphSymbols =
+    checkedShellScript
+      {
+        name = "postgrest-hsie-graph-symbols";
+        docs = "Create a PNG graph of symbols imported within the codebase.";
+      }
+      ''${hsieMinimalImports} graph-symbols | ${graphviz}/bin/dot -Tpng -o "$1"'';
 in
 buildEnv {
   name = "postgrest-devtools";
@@ -142,6 +160,9 @@ buildEnv {
     run.bin
     clean.bin
     check.bin
-    importsgraph.bin
+    dumpMinimalImports.bin
+    hsieMinimalImports.bin
+    hsieGraphModules.bin
+    hsieGraphSymbols.bin
   ];
 }

nix/hsie/Main.hs

@@ -0,0 +1,358 @@
+{-# LANGUAGE DeriveAnyClass    #-}
+{-# LANGUAGE DeriveGeneric     #-}
+{-# LANGUAGE NamedFieldPuns    #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards   #-}
+{-# LANGUAGE TupleSections     #-}
+{-# LANGUAGE TypeFamilies      #-}
+
+-- | Haskell Imports and Exports tool
+--
+-- This tool parses imports and exports from Haskell source files and provides
+-- analysis on these imports. For example, you can check whether consistent
+-- import aliases are used across your codebase.
+
+module Main (main) where
+
+import qualified Data.Aeson                              as JSON
+import qualified Data.ByteString.Lazy.Char8              as LBS8
+import qualified Data.Csv                                as Csv
+import qualified Data.Map                                as Map
+import qualified Data.Set                                as Set
+import qualified Data.Text                               as T
+import qualified Data.Text.IO                            as T
+import qualified Dot
+import qualified GHC
+import qualified Language.Haskell.GHC.ExactPrint.Parsers as ExactPrint
+import qualified Options.Applicative                     as O
+import qualified System.FilePath                         as FP
+
+import Data.Aeson.Encode.Pretty   (encodePretty)
+import Data.Function              ((&))
+import Data.List                  (intercalate)
+import Data.Maybe                 (catMaybes, mapMaybe)
+import Data.Text                  (Text)
+import GHC.Generics               (Generic)
+import HsExtension                (GhcPs)
+import Module                     (moduleNameString)
+import OccName                    (occNameString)
+import RdrName                    (rdrNameOcc)
+import System.Directory.Recursive (getFilesRecursive)
+import System.Exit                (exitFailure)
+
+-- TYPES
+
+data Options =
+  Options
+    { command :: Command
+    , sources :: [FilePath]
+    }
+
+data Command
+  = Dump OutputFormat
+  | GraphSymbols
+  | GraphModules
+  | CheckAliases
+  | CheckWildcards [Text]
+
+data OutputFormat = OutputCsv | OutputJson
+
+data ImportedSymbol =
+  ImportedSymbol
+    { impFromModule :: Text
+    , impModule     :: Text
+    , impQualified  :: ImportQualified
+    , impAlias      :: Maybe Text
+    , impType       :: ImportType
+    , impSymbol     :: Maybe Text
+    , impInternal   :: ModuleInternal
+    , impSource     :: FilePath
+    , impFile       :: FilePath
+    }
+    deriving (Generic, Csv.ToNamedRecord, Csv.DefaultOrdered, JSON.ToJSON)
+
+data ImportQualified
+  = Qualified
+  | NotQualified
+  deriving (Eq, Generic, JSON.ToJSON)
+
+instance Csv.ToField ImportQualified where
+  toField Qualified    = "qualified"
+  toField NotQualified = "not qualified"
+
+data ModuleInternal
+  = Internal
+  | External
+  deriving (Eq, Generic, JSON.ToJSON)
+
+instance Csv.ToField ModuleInternal where
+  toField Internal = "internal"
+  toField External = "external"
+
+data ImportType
+  = Wildcard
+  | Hiding
+  | Explicit
+  deriving (Eq, Generic, JSON.ToJSON)
+
+instance Csv.ToField ImportType where
+  toField Wildcard = "wildcard"
+  toField Hiding   = "hiding"
+  toField Explicit = "explicit"
+
+-- | Mapping of modules to their aliases and to the files they are found in
+type ModuleAliases = [(Text, [(Text, [FilePath])])]
+
+-- | Mapping of modules to files
+type WildcardImports = [(FilePath, [Text])]
+
+
+-- MAIN
+
+main :: IO ()
+main =
+  run =<< O.customExecParser prefs infoOpts
+  where
+    prefs = O.prefs $ O.subparserInline <> O.showHelpOnEmpty
+    infoOpts =
+      O.info (O.helper <*> opts) $
+        O.fullDesc
+        <> O.header "hsie - Swiss army knife for HaSkell Imports and Exports"
+        <> O.progDesc "Parse Haskell code to analyze imports and exports"
+    opts =
+      Options <$> commandOption <*> O.some srcOption
+    srcOption =
+      O.argument O.str $
+        O.metavar "SRCDIR"
+        <> O.help "Haskell source directory"
+        <> O.action "directory"
+    commandOption =
+      O.subparser $
+        command "dump-imports" "Dump imported symbols as CSV or JSON"
+          (Dump <$> jsonOutputFlag)
+        <> command "graph-modules" "Print dot graph of module imports"
+             (pure GraphModules)
+        <> command "graph-symbols" "Print dot graph of symbol imports"
+             (pure GraphSymbols)
+        <> command "check-aliases"
+             "Check that aliases of imported modules are consistent"
+             (pure CheckAliases)
+        <> command "check-wildcards"
+             "Check that no modules are imported as unqualified wildcards"
+             (CheckWildcards <$> O.many okModuleOption)
+    command name desc options =
+      O.command name . O.info (O.helper <*> options) $ O.progDesc desc
+    jsonOutputFlag =
+      O.flag OutputCsv OutputJson $
+        O.long "json" <> O.short 'j' <> O.help "Output JSON"
+    okModuleOption =
+      O.strOption $
+        O.long "ok"
+        <> O.short 'o'
+        <> O.metavar "OKMODULE"
+        <> O.help "Module that is ok to import as unqualified wildcard"
+
+run :: Options -> IO ()
+run Options{command, sources} =
+  runCommand command . markInternal . concat =<< mapM sourceSymbols sources
+  where
+    runCommand :: Command -> [ImportedSymbol] -> IO ()
+    runCommand (Dump format) = LBS8.putStr . dump format
+    runCommand GraphSymbols = T.putStr . symbolsGraph
+    runCommand GraphModules = T.putStr . Dot.encode . modulesGraph
+    runCommand CheckAliases = runInconsistentAliases . inconsistentAliases
+    runCommand (CheckWildcards okModules) = runWildcards . wildcards okModules
+
+    runInconsistentAliases :: ModuleAliases -> IO ()
+    runInconsistentAliases [] = T.putStrLn "No inconsistent module aliases found."
+    runInconsistentAliases xs = T.putStr (formatInconsistentAliases xs) >> exitFailure
+
+    runWildcards :: WildcardImports -> IO ()
+    runWildcards [] = T.putStrLn "No unwanted wildcard imports found."
+    runWildcards xs = T.putStr (formatWildcards xs) >> exitFailure
+
+-- | Mark imports from modules that are among the analyzed ones as internal.
+markInternal :: [ImportedSymbol] -> [ImportedSymbol]
+markInternal symbols =
+  fmap mark symbols
+  where
+    mark s = s { impInternal = if isInternal s then Internal else External }
+    isInternal = flip Set.member internalModules . impModule
+    internalModules = Set.fromList $ fmap impFromModule symbols
+
+
+-- SYMBOLS
+
+-- | Parse all imported symbols from a source of Haskell source files
+sourceSymbols :: FilePath -> IO [ImportedSymbol]
+sourceSymbols source = do
+  files <- filterExts [".hs", ".imports"] <$> getFilesRecursive source
+  concat <$> mapM moduleSymbols files
+  where
+    filterExts exts = filter $ flip elem exts . FP.takeExtension
+    moduleSymbols filepath = do
+      GHC.HsModule{..} <- parseModule filepath
+      return $ concatMap (importSymbols source filepath . GHC.unLoc) hsmodImports
+
+-- | Parse a Haskell module
+parseModule :: String -> IO (GHC.HsModule GhcPs)
+parseModule filepath = do
+  result <- ExactPrint.parseModule filepath
+  case result of
+    Right (_, hsmod) ->
+      return $ GHC.unLoc hsmod
+    Left (loc, err) ->
+      fail $ "Error with " <> show filepath <> " at " <> show loc <> ": " <> err
+
+-- | Symbols imported in an import declaration.
+--
+-- If the import is a wildcard, i.e. no symbols are selected for import, then
+-- only one item is returned.
+importSymbols :: FilePath -> FilePath -> GHC.ImportDecl GhcPs -> [ImportedSymbol]
+importSymbols _ _  (GHC.XImportDecl _) = mempty
+importSymbols source filepath GHC.ImportDecl{..} =
+  case ideclHiding of
+    Just (hiding, syms) ->
+      symbol (if hiding then Hiding else Explicit) . Just . GHC.unLoc <$> GHC.unLoc syms
+    Nothing ->
+      [ symbol Wildcard Nothing ]
+  where
+    symbol hiding sym =
+      ImportedSymbol
+        { impFile = relativePath filepath
+        , impSource = source
+        , impFromModule = T.pack $ moduleFromPath filepath
+        , impModule = T.pack . moduleNameString . GHC.unLoc $ ideclName
+        , impQualified = if ideclQualified then Qualified else NotQualified
+        , impAlias = T.pack . moduleNameString . GHC.unLoc <$> ideclAs
+        , impInternal = External
+        , impType = hiding
+        , impSymbol = T.pack . occNameString . rdrNameOcc . GHC.ieName <$> sym
+        }
+    moduleFromPath =
+      intercalate "." . FP.splitDirectories . FP.dropExtension . relativePath
+    relativePath = FP.makeRelative source
+
+
+-- DUMP
+
+-- | Dump list of symbols as CSV or JSON
+dump :: OutputFormat -> [ImportedSymbol] -> LBS8.ByteString
+dump OutputCsv  = Csv.encodeDefaultOrderedByName
+dump OutputJson = encodePretty
+
+
+-- ALIASES
+
+-- | Find modules that are imported under different aliases
+inconsistentAliases :: [ImportedSymbol] -> ModuleAliases
+inconsistentAliases symbols =
+  fmap moduleAlias symbols
+    & foldr insertSetMapMap Map.empty
+    & Map.map (aliases . Map.toList)
+    & Map.filter ((<) 1 . length)
+    & Map.toList
+  where
+    moduleAlias ImportedSymbol{..} =
+      (impModule, impAlias, FP.joinPath [impSource, impFile])
+    insertSetMapMap (k1, k2, v) =
+      Map.insertWith (Map.unionWith Set.union) k1
+        (Map.singleton k2 $ Set.singleton v)
+    aliases :: [(Maybe Text, Set.Set FilePath)] -> [(Text, [FilePath])]
+    aliases = mapMaybe (\(k, v) -> fmap (, Set.toList v) k)
+
+formatInconsistentAliases :: ModuleAliases -> Text
+formatInconsistentAliases modules =
+  "The following imports have inconsistent aliases:\n\n"
+    <> T.concat (fmap formatModule modules)
+  where
+    formatModule (modName, aliases) =
+      "Module '"
+        <> modName
+        <> "' has the aliases:\n"
+        <> T.concat (fmap formatAlias aliases)
+        <> "\n"
+    formatAlias (alias, sourceFiles) =
+      "  '"
+        <> alias
+        <> "' in file"
+        <> (if length sourceFiles > 2 then "s" else "")
+        <> ":\n"
+        <> T.concat (fmap formatFile sourceFiles)
+    formatFile sourceFile =
+      "    " <> T.pack sourceFile <> "\n"
+
+
+-- WILDCARDS
+
+-- | Find modules that are imported as wildcards, excluding whitelisted modules.
+--
+-- Wildcard imports are ones that are not qualified and do not specify which
+-- symbols should be imported.
+wildcards :: [Text] -> [ImportedSymbol] -> WildcardImports
+wildcards okModules =
+  groupByFile . filter isWildcard . filter (not . isOkModule)
+  where
+    isWildcard ImportedSymbol{..} =
+      impQualified == NotQualified && impType /= Explicit
+    isOkModule = flip Set.member (Set.fromList okModules) . impModule
+    groupByFile = Map.toList . fmap Set.toList . foldr insertMap Map.empty
+    insertMap ImportedSymbol{..} =
+      Map.insertWith Set.union impFile (Set.singleton impModule)
+
+formatWildcards :: WildcardImports -> Text
+formatWildcards files =
+  "Modules in the following files were imported as wildcards:\n\n"
+    <> T.concat (fmap formatFile files)
+  where
+    formatFile (filepath, modules) =
+      "In " <> T.pack filepath <> ":\n" <> T.concat (fmap formatModule modules) <> "\n"
+    formatModule moduleName = "  " <> moduleName <> "\n"
+
+
+-- GRAPHS
+
+modulesGraph :: [ImportedSymbol] -> Dot.DotGraph
+modulesGraph symbols =
+  Dot.DotGraph Dot.Strict Dot.Directed (Just "Modules") $ fmap edge edges
+  where
+    edge (from, to) =
+      Dot.StatementEdge $ Dot.EdgeStatement
+        (Dot.ListTwo (edgeNode from) (edgeNode to) mempty) mempty
+    edgeNode t = Dot.EdgeNode $ Dot.NodeId (Dot.Id t) Nothing
+    edges = unique . fmap edgeTuple . filter ((==) Internal . impInternal) $ symbols
+    edgeTuple ImportedSymbol{..} = (impFromModule, impModule)
+    unique = Set.toList . Set.fromList
+
+-- Building Text directly as the Dot package currently doesn't support subgraphs.
+symbolsGraph :: [ImportedSymbol] -> Text
+symbolsGraph symbols =
+  "digraph Symbols {\n"
+    <> "  rankdir=LR\n"
+    <> "  ranksep=5\n"
+    <> T.concat (fmap edge edges)
+    <> T.concat (fmap cluster symbolsByModule)
+    <> "}\n"
+  where
+    edge (from, to, symbol) =
+      "  "
+        <> quoted from
+        <> " -> "
+        <> quoted (to <> maybe "" ("." <>) symbol)
+        <> "\n"
+    cluster (moduleName, clusterSymbols) =
+      "  subgraph "
+        <> quoted ("cluster_" <> moduleName)
+        <> " {\n"
+        <> "    " <> quoted moduleName <> "\n"
+        <> T.concat (fmap (clusterNode moduleName) clusterSymbols)
+        <> "  }\n"
+    clusterNode moduleName symbol =
+      "    " <> quoted (moduleName <> "." <> symbol) <> "\n"
+    quoted t = "\"" <> t <> "\""
+    edges = unique . fmap edgeTuple . filter ((==) Internal . impInternal) $ symbols
+    edgeTuple ImportedSymbol{..} = (impFromModule, impModule, impSymbol)
+    unique = Set.toList . Set.fromList
+    symbolsByModule =
+      Map.toList . Map.map (catMaybes . Set.toList) . foldr insertMap Map.empty $ edges
+    insertMap (_, to, symbol) = Map.insertWith Set.union to $ Set.singleton symbol

nix/hsie/README.md

@@ -0,0 +1,67 @@
+# hsie - Swiss army knife for HaSkell Imports and Exports
+
+This tool parses Haskell source code to analyse the imports and exports in a
+project. It's available in PostgREST's `nix-shell` by default.
+
+## Dumping imports
+
+Given source code in the directories `src` and `main`, for example, you can run:
+
+```
+hsie dump-imports src main
+```
+
+This dumps all imports of the modules in the given directory to a CSV file,
+printed on `stdout`.
+
+To dump to a JSON file (e.g., to further process with `jq`), add the `--json`
+flag:
+
+```
+hsie dump-imports --json src main
+```
+
+## Graphing imports
+
+The tool can generate `graphviz` graphs of module and symbol imports by printing
+a file to `stdout` that can directly be rendered with `dot`:
+
+```
+hsie graph-modules src main | dot -Tpng -o modules.png
+```
+
+The command `graph-modules` prints a graph of which modules insert which other
+modules. `graph-symbols` shows which symbols are imported from which modules.
+
+## Checking imports
+
+To check whether modules are imported under consistent aliases in your project,
+run:
+
+```
+hsie check-aliases main src
+```
+
+This will exit with a non-zero exit code if any inconsistent aliases are found.
+
+The following command checks whether any modules are imported as wildcards, i.e.
+not qualified and without specifying symbols.
+
+```
+hsie check-wildcards main src
+```
+
+To whitelist certain modules to be imported as wildcards, use `--ok`:
+
+```
+hsie check-wildcards main src --ok Protolude --ok Test.Module
+```
+
+## Current limitations
+
+This tool uses the GHC parser to parse Haskell source code. Language extensions
+required to parse each file are detected based on the `{-# LANGUAGE ... #-}`
+pragmas. If they are not available (e.g., as they are listed as default
+extensions in the `.cabal` file), parses may fail. We can fix this by using
+an extended set of non-conflicting extensions by default, as `hlint` does for
+example.

nix/hsie/default.nix

@@ -0,0 +1,30 @@
+{ ghcWithPackages
+, runCommand
+}:
+let
+  name = "hsie";
+  src = ./Main.hs;
+  modules = ps: [
+    ps.aeson
+    ps.aeson-pretty
+    ps.cassava
+    ps.dir-traverse
+    ps.dot
+    ps.ghc-exactprint
+    ps.optparse-applicative
+  ];
+  ghc = ghcWithPackages modules;
+  hsie =
+    runCommand "haskellimports" { inherit name src; }
+      "${ghc}/bin/ghc -O -Werror -Wall -package ghc $src -o $out";
+  bin =
+    runCommand name { inherit hsie name; }
+      ''
+        mkdir -p $out/bin
+        ln -s $hsie $out/bin/$name
+      '';
+  bashCompletion =
+    runCommand "${name}-bash-completion" { inherit bin name; }
+      "$bin/bin/$name --bash-completion-script $bin/bin/$name > $out";
+in
+hsie // { inherit bashCompletion bin; }

postgrest.cabal

@@ -32,7 +32,6 @@ flag hpc
 library
   default-language:   Haskell2010
   default-extensions: OverloadedStrings
-                      QuasiQuotes
                       NoImplicitPrelude
   hs-source-dirs:     src
   exposed-modules:    PostgREST.ApiRequest
@@ -116,7 +115,6 @@ library
 executable postgrest
   default-language:   Haskell2010
   default-extensions: OverloadedStrings
-                      QuasiQuotes
                       NoImplicitPrelude
   hs-source-dirs:     main
   main-is:            Main.hs

shell.nix

@@ -31,6 +31,7 @@ lib.overrideDerivation postgrest.env (
         postgrest.devtools
         postgrest.tests
         postgrest.style
+        postgrest.hsie.bin
       ]
       ++ lib.optional memoryTests postgrest.tests.memoryTests
       ++ lib.optional docker postgrest.docker
@@ -47,6 +48,7 @@ lib.overrideDerivation postgrest.env (
         complete -F _command postgrest-with-postgresql-10
         complete -F _command postgrest-with-postgresql-9.6
         complete -F _command postgrest-with-postgresql-9.5
+        source ${postgrest.hsie.bashCompletion}
       '';
   }
 )

src/PostgREST/Config.hs

@@ -16,6 +16,7 @@ Other hardcoded options such as the minimum version number also belong here.
 {-# LANGUAGE FlexibleInstances     #-}
 {-# LANGUAGE LambdaCase            #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE QuasiQuotes           #-}
 {-# LANGUAGE ScopedTypeVariables   #-}
 {-# LANGUAGE TemplateHaskell       #-}
 {-# OPTIONS_GHC -fno-warn-type-defaults #-}

src/PostgREST/Private/QueryFragment.hs

@@ -1,4 +1,5 @@
 {-# LANGUAGE LambdaCase  #-}
+{-# LANGUAGE QuasiQuotes #-}
 {-|
 Module      : PostgREST.Private.QueryFragment
 Description : Helper functions for PostgREST.QueryBuilder.

src/PostgREST/Statements.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE QuasiQuotes #-}
 {-|
 Module      : PostgREST.Statements
 Description : PostgREST single SQL statements.