Merge pull request #885 from github/constraint-alias

Introduce DefaultFields Constraint alias

src/Data/Record.hs

@@ -1,9 +1,16 @@
-{-# LANGUAGE DataKinds, GADTs, KindSignatures, MultiParamTypeClasses, TypeOperators #-}
+{-# LANGUAGE DataKinds, GADTs, KindSignatures, MultiParamTypeClasses, TypeOperators, ConstraintKinds #-}
 module Data.Record where
 
 import GHC.Show
 import Prologue
 import Test.QuickCheck
+import Category
+import Range
+import SourceSpan
+
+
+-- | A type alias for HasField constraints commonly used throughout semantic-diff.
+type DefaultFields fields = (HasField fields Category, HasField fields Range, HasField fields SourceSpan)
 
 -- | A type-safe, extensible record structure.
 -- |

src/DiffSummary.hs

@@ -81,20 +81,17 @@ data DiffSummary a = DiffSummary {
 } deriving (Eq, Functor, Show, Generic)
 
 -- Returns a list of diff summary texts given two source blobs and a diff.
-diffSummaries :: (HasCategory leaf, HasField fields Category, HasField fields Range, HasField fields SourceSpan) =>
-                  Both SourceBlob ->
-                  SyntaxDiff leaf fields ->
-                  [JSONSummary Text SourceSpans]
+diffSummaries :: (HasCategory leaf, DefaultFields fields) => Both SourceBlob -> SyntaxDiff leaf fields -> [JSONSummary Text SourceSpans]
 diffSummaries blobs diff = summaryToTexts =<< diffToDiffSummaries (source <$> blobs) diff
 
--- Takes a 'DiffSummary' and returns a list of summary texts representing the LeafInfos
--- in that 'DiffSummary'.
+-- Takes a 'DiffSummary DiffInfo' and returns a list of JSON Summaries whose text summaries represent the LeafInfo summaries of the 'DiffSummary'.
 summaryToTexts :: DiffSummary DiffInfo -> [JSONSummary Text SourceSpans]
-summaryToTexts DiffSummary{..} = (\jsonSummary ->
-  jsonSummary { summary = show $ summary jsonSummary <+> parentContexts parentAnnotation }) <$> summaries patch
+summaryToTexts DiffSummary{..} = appendParentContexts <$> summaries patch
+  where appendParentContexts jsonSummary =
+          jsonSummary { summary = show $ summary jsonSummary <+> parentContexts parentAnnotation }
 
 -- Returns a list of 'DiffSummary' given two source blobs and a diff.
-diffToDiffSummaries :: (HasCategory leaf, HasField fields Category, HasField fields Range, HasField fields SourceSpan) => Both (Source Char) -> SyntaxDiff leaf fields -> [DiffSummary DiffInfo]
+diffToDiffSummaries :: (HasCategory leaf, DefaultFields fields) => Both (Source Char) -> SyntaxDiff leaf fields -> [DiffSummary DiffInfo]
 diffToDiffSummaries sources = para $ \diff ->
   let
     diff' = free (Prologue.fst <$> diff)
@@ -159,7 +156,7 @@ toLeafInfos leaf = pure . flip JSONSummary (sourceSpan leaf) $ case leaf of
   node -> panic $ "Expected a leaf info but got a: " <> show node
 
 -- Returns a text representing a specific term given a source and a term.
-toTermName :: forall leaf fields. (HasCategory leaf, HasField fields Category, HasField fields Range) => Source Char -> SyntaxTerm leaf fields -> Text
+toTermName :: forall leaf fields. (HasCategory leaf, DefaultFields fields) => Source Char -> SyntaxTerm leaf fields -> Text
 toTermName source term = case unwrap term of
   S.AnonymousFunction params _ -> "anonymous" <> paramsToArgNames params
   S.Fixed children -> fromMaybe "branch" $ (toCategoryName . category) . extract <$> head children
@@ -246,7 +243,7 @@ parentContexts contexts = hsep $ either identifiableDoc annotatableDoc <$> conte
 toDoc :: Text -> Doc
 toDoc = string . toS
 
-termToDiffInfo :: (HasCategory leaf, HasField fields Category, HasField fields Range, HasField fields SourceSpan) => Source Char -> SyntaxTerm leaf fields -> DiffInfo
+termToDiffInfo :: (HasCategory leaf, DefaultFields fields) => Source Char -> SyntaxTerm leaf fields -> DiffInfo
 termToDiffInfo blob term = case unwrap term of
   S.Indexed children -> BranchInfo (termToDiffInfo' <$> children) (toCategoryName term) BIndexed
   S.Fixed children -> BranchInfo (termToDiffInfo' <$> children) (toCategoryName term) BFixed
@@ -263,7 +260,7 @@ termToDiffInfo blob term = case unwrap term of
 -- | For a DiffSummary without a parentAnnotation, we append a parentAnnotation with the first identifiable term.
 -- | For a DiffSummary with a parentAnnotation, we append the next annotatable term to the extant parentAnnotation.
 -- | If a DiffSummary already has a parentAnnotation, and a (grand) parentAnnotation, then we return the summary without modification.
-appendSummary :: (HasCategory leaf, HasField fields Range, HasField fields Category) => Source Char -> SyntaxTerm leaf fields -> DiffSummary DiffInfo -> DiffSummary DiffInfo
+appendSummary :: (HasCategory leaf, DefaultFields fields) => Source Char -> SyntaxTerm leaf fields -> DiffSummary DiffInfo -> DiffSummary DiffInfo
 appendSummary source term summary =
   case (parentAnnotation summary, identifiable term, annotatable term) of
     ([], Identifiable _, _) -> appendParentAnnotation Left

src/Diffing.hs

@@ -127,7 +127,7 @@ diffCostWithCachedTermCosts diff = unCost $ case runFree diff of
   Pure patch -> sum (cost . extract <$> patch)
 
 -- | Returns a rendered diff given a parser, diff arguments and two source blobs.
-textDiff :: (HasField fields SourceSpan, HasField fields Category, HasField fields Cost, HasField fields Range) => Parser (Syntax Text) (Record fields) -> DiffArguments -> Both SourceBlob -> IO Output
+textDiff :: (DefaultFields fields, HasField fields Cost) => Parser (Syntax Text) (Record fields) -> DiffArguments -> Both SourceBlob -> IO Output
 textDiff parser arguments = diffFiles parser $ case format arguments of
   Split -> split
   Patch -> patch
@@ -143,7 +143,7 @@ truncatedDiff arguments sources = pure $ case format arguments of
   Summary -> SummaryOutput mempty
 
 -- | Prints a rendered diff to stdio or a filepath given a parser, diff arguments and two source blobs.
-printDiff :: (HasField fields SourceSpan, HasField fields Category, HasField fields Cost, HasField fields Range) => Parser (Syntax Text) (Record fields) -> DiffArguments -> Both SourceBlob -> IO ()
+printDiff :: (DefaultFields fields, HasField fields Cost) => Parser (Syntax Text) (Record fields) -> DiffArguments -> Both SourceBlob -> IO ()
 printDiff parser arguments sources = do
   rendered <- textDiff parser arguments sources
   let renderedText = case rendered of

src/Renderer/Summary.hs

@@ -1,19 +1,16 @@
 {-# LANGUAGE TupleSections, ScopedTypeVariables #-}
 module Renderer.Summary where
 
-import Category
 import Prologue
 import Renderer
 import Data.Record
-import Range
 import DiffSummary
 import Data.Map as Map hiding (null)
 import Source
-import SourceSpan
 import Data.Aeson
 import Data.List as List
 
-summary :: (HasField fields Category, HasField fields Range, HasField fields SourceSpan) => Renderer (Record fields)
+summary :: (DefaultFields fields) => Renderer (Record fields)
 summary blobs diff = SummaryOutput $ Map.fromList [
     ("changes", changes),
     ("errors", errors)