Add --no-config-format flag. Fixes #300.

CHANGELOG.md

@@ -13,6 +13,8 @@ Bugfixes:
 New features:
 - Add support for starting a repl within a folder which has not been setup as a spago project (#168)
 - Add `--format` flag to `spago docs` (#294)
+- Add `--no-config-format` global flag. Fixes #300. Skips formatting
+  `spago.dhall` during operations.
 
 ## [0.8.5] - 2019-06-18
 

README.md

@@ -309,6 +309,17 @@ $ spago run --node-args "arg1 arg2"
 ```
 
 
+### Avoid re-formatting the `spago.dhall` and `packages.dhall` with each command
+
+You can pass the `--no-config-format` or `-F` global flag:
+
+``` bash
+$ spago build -F
+Installation complete.
+Build succeeded.
+```
+
+
 ### Test my project
 
 You can also test your project with `spago`:

app/Spago.hs

@@ -114,6 +114,7 @@ parser = do
   where
     force           = CLI.switch "force" 'f' "Overwrite any project found in the current directory"
     verbose         = CLI.switch "verbose" 'v' "Enable additional debug logging, e.g. printing `purs` commands"
+    noConfigFormat  = CLI.switch "no-config-format" 'F' "Disable formatting the configuration file `spago.dhall`"
     watchBool       = CLI.switch "watch" 'w' "Watch for changes in local files and automatically rebuild"
     noInstallBool   = CLI.switch "no-install" 'n' "Don't run the automatic installation of packages"
     clearScreenBool = CLI.switch "clear-screen" 'l' "Clear the screen on rebuild (watch mode only)"
@@ -160,7 +161,7 @@ parser = do
     replPackageNames = CLI.many $ CLI.opt (Just . PackageName) "dependency" 'd' "Package name to add to the REPL as dependency"
     passthroughArgs = many $ CLI.arg (Just . ExtraArg) " ..any `purs compile` option" "Options passed through to `purs compile`; use -- to separate"
     buildOptions = BuildOptions <$> limitJobs <*> cacheFlag <*> watch <*> clearScreen <*> sourcePaths <*> noInstall <*> passthroughArgs
-    globalOptions = GlobalOptions <$> verbose
+    globalOptions = GlobalOptions <$> verbose <*> noConfigFormat
     packagesFilter =
       let wrap = \case
             "direct"     -> Just DirectDeps

src/Spago/Config.hs

@@ -173,11 +173,12 @@ addSourcePaths expr = expr
 withConfigAST :: Spago m => (Expr -> m Expr) -> m ()
 withConfigAST transform = do
   rawConfig <- liftIO $ Dhall.readRawExpr pathText
+  hasDontFormatConfig <- asks dontFormatConfig
   case rawConfig of
     Nothing -> die Messages.cannotFindConfig
     Just (header, expr) -> do
       newExpr <- transformMExpr transform expr
-      liftIO $ Dhall.writeRawExpr pathText (header, newExpr)
+      liftIO $ Dhall.writeRawExpr hasDontFormatConfig pathText (header, newExpr)
   where
     transformMExpr
       :: Spago m

src/Spago/Dhall.hs

@@ -50,14 +50,15 @@ readRawExpr pathText = do
     else (pure Nothing)
 
 
-writeRawExpr :: Text -> (Text, DhallExpr Dhall.Import) -> IO ()
-writeRawExpr pathText (header, expr) = do
+writeRawExpr :: Bool -> Text -> (Text, DhallExpr Dhall.Import) -> IO ()
+writeRawExpr hasDontFormatConfig pathText (header, expr) = do
   -- After modifying the expression, we have to check if it still typechecks
   -- if it doesn't we don't write to file.
   resolvedExpr <- Dhall.Import.load expr
-  throws (Dhall.TypeCheck.typeOf resolvedExpr)
-  writeTextFile (pathFromText pathText) $ prettyWithHeader header expr <> "\n"
-  format pathText
+  _ <- throws (Dhall.TypeCheck.typeOf resolvedExpr)
+  unless hasDontFormatConfig $ do
+    writeTextFile (pathFromText pathText) $ prettyWithHeader header expr <> "\n"
+    format pathText
 
 
 -- | Returns a Dhall Text literal from a lone string

src/Spago/PackageSet.hs

@@ -116,7 +116,7 @@ upgradePackageSet = do
           echo $ "Upgrading the package set version to " <> quotedTag
           let newExpr = fmap (upgradeImports releaseTagName) expr
           echo $ Messages.upgradingPackageSet releaseTagName
-          liftIO $ Dhall.writeRawExpr pathText (header, newExpr)
+          liftIO $ Dhall.writeRawExpr False pathText (header, newExpr)
           -- If everything is fine, refreeze the imports
           freeze
   where

src/Spago/Prelude.hs

@@ -116,6 +116,7 @@ instance Show SpagoError where
 
 data GlobalOptions = GlobalOptions
   { debug :: Bool
+  , dontFormatConfig :: Bool
   }
 
 type Spago m =