tame the strings

Adds a PrettyPrint typeclass which operates on Text and should replace
Show, since constantly converting strings from linked lists to arrays
seems somewhat silly.

4 files changed, 55 insertions, 43 deletions

diff --git a/lib/CheckMap.hs b/lib/CheckMap.hs
index 97e6a8c..0ff3fae 100644
--- a/lib/CheckMap.hs
+++ b/lib/CheckMap.hs
@@ -22,7 +22,7 @@ import           Properties                 (checkProperty)
 import           Tiled2                     (Layer (layerName, layerProperties),
                                              Tiledmap (tiledmapLayers),
                                              loadTiledmap)
-import           Util                       (showText)
+import           Util                       (prettyprint, PrettyPrint (prettyprint))
 
 -- | What this linter produces: lints for a single map
 data MapResult a = MapResult
@@ -61,35 +61,34 @@ checkLayer :: Layer -> LintWriter ()
 checkLayer layer =
   mapM_ (checkProperty layer) (layerProperties layer)
 
-
--- this instance of show produces a reasonably human-readable
--- list of lints that can be shown e.g. on a console
-instance Show a => Show (MapResult a) where
-  show mapResult = concat $ prettyGeneral <> prettyLayer
+-- human-readable lint output, e.g. for consoles
+instance PrettyPrint a => PrettyPrint (MapResult a) where
+  prettyprint mapResult = T.concat $ prettyGeneral <> prettyLayer
     where
       -- TODO: this can be simplified further
-      prettyLayer :: [String]
+      prettyLayer :: [Text]
       prettyLayer = mapMaybe
-        (\(name, lints) -> T.unpack <$> showResult name lints)
+        (uncurry showResult)
         (maybe [] toList . mapresultLayer $ mapResult)
-      prettyGeneral :: [String]
-      prettyGeneral = show <$> mapresultGeneral mapResult
+      prettyGeneral :: [Text]
+      prettyGeneral = prettyprint <$> mapresultGeneral mapResult
 
 
 -- TODO: possibly expand this to something more detailed?
 showContext :: Text -> Text
 showContext ctxt = " (in layer " <> ctxt <> ")\n"
 
--- | pretty-printer for a LintResult. Isn't an instance of Show since
+-- | pretty-printer for a LintResult. Isn't an instance of PrettyPrint since
 -- it needs to know about the result's context (yes, there could be
 -- a wrapper type for that – but I wasn't really in the mood)
-showResult :: Show a => Text -> LintResult a -> Maybe Text
-showResult ctxt (LintResult (Left hint)) = Just $ "ERROR: " <> hintMsg hint <> showContext ctxt
-showResult _ (LintResult (Right (_, []))) = Nothing
-showResult ctxt (LintResult (Right (_, hints))) = Just $ T.concat (mapMaybe showHint hints)
+showResult :: Text -> LintResult a -> Maybe Text
+showResult ctxt (LintResult res) = case res of
+  Left hint -> Just $ "ERROR: " <> hintMsg hint <> showContext ctxt
+  Right (_, []) -> Nothing
+  Right (_, hints) -> Just $ T.concat (mapMaybe showHint hints)
   where
     -- TODO: make the "log level" configurable
-    showHint Hint { hintMsg, hintLevel } = case hintLevel of
+    showHint hint = case hintLevel hint of
       Info -> Nothing
-      _    -> Just $ showText hintLevel <> ": " <> hintMsg <> ctxtHint
+      _    -> Just $ prettyprint hint <> ctxtHint
     ctxtHint = showContext ctxt
diff --git a/lib/LintWriter.hs b/lib/LintWriter.hs
index 8e45812..10c727d 100644
--- a/lib/LintWriter.hs
+++ b/lib/LintWriter.hs
@@ -10,9 +10,11 @@ import           Control.Monad.Trans.Maybe ()
 import           Control.Monad.Writer      (MonadTrans (lift),
                                             MonadWriter (tell), WriterT)
 import           Data.Aeson                (ToJSON (toJSON))
-import           Data.Text                 (Text, unpack)
+import           Data.Text                 (Text)
 import           GHC.Generics              (Generic)
 
+import Util (PrettyPrint(..), showText)
+
 -- | Levels of errors and warnings, collectively called
 -- "Hints" until I can think of some better name
 data Level = Warning | Suggestion | Info | Forbidden | Error | Fatal
@@ -24,9 +26,9 @@ data Hint = Hint
   , hintMsg   :: Text }
   deriving (Generic, ToJSON)
 
-instance Show Hint where
-  show Hint { hintMsg, hintLevel } =
-    show hintLevel <> ": " <> unpack hintMsg
+instance PrettyPrint Hint where
+  prettyprint Hint { hintMsg, hintLevel } =
+    showText hintLevel <> ": " <> hintMsg
 
 -- shorter constructor
 hint :: Level -> Text -> Hint
diff --git a/lib/Properties.hs b/lib/Properties.hs
index 10cbf2c..f4dff3d 100644
--- a/lib/Properties.hs
+++ b/lib/Properties.hs
@@ -11,7 +11,7 @@ import           Data.Aeson                as Aeson (Value (String))
 import           Data.Map                  (Map, (!?))
 import           Data.Text                 (Text)
 import           Tiled2                    (Layer (layerProperties))
-import           Util                      (quote, showAeson)
+import           Util                      (prettyprint)
 
 import           LintWriter                (Hint, LintWriter, Level(..), hint,
                                             assertWarn, complain, forbid, info,
@@ -54,7 +54,7 @@ checkProperty' layer prop ty = case ty of
     "jitsiRoom" -> do
       propEqual prop "type" "string"
       urlValue <- lift $ getAttr prop "value"
-      info $ "found jitsi room: " <> showAeson urlValue
+      info $ "found jitsi room: " <> prettyprint urlValue
       suggestPropertyValue "jitsiTrigger" "onaction"
     "jitsiTrigger" ->
       requireProperty "jitsiRoom"
@@ -79,16 +79,17 @@ checkProperty' layer prop ty = case ty of
     "startLayer" -> pure ()
       -- could also make this a "hard error" (i.e. Left), but then it
       -- stops checking other properties as checkLayer short-circuits.
-    _ -> warn $ "unknown property type " <> quote ty
+    _ -> warn $ "unknown property type " <> prettyprint ty
     where
       -- | require some property in this layer
       requireProperty name = unless (hasProperty name layer)
-        $ complain $ "property "<>quote name<>" requires property "<>quote ty
+        $ complain $ "property "<>prettyprint name<>" requires property "<>prettyprint ty
       -- | This property is forbidden and should not be used
-      isForbidden = forbid $ "property " <> quote ty <> " should not be used"
+      isForbidden = forbid $ "property " <> prettyprint ty <> " should not be used"
       -- TODO: check if the property has the correct value
+      suggestPropertyValue :: Text -> Text -> LintWriter ()
       suggestPropertyValue name value = unless (hasProperty name layer)
-        $ suggest $ "set property " <> quote name <> " to " <> quote value
+        $ suggest $ "set property " <> prettyprint name <> " to " <> prettyprint value
 
 
 
@@ -108,6 +109,6 @@ getAttr props name = unwrapWarn msg $ props !? name
 propEqual :: Properties -> Text -> Aeson.Value -> LintWriter ()
 propEqual props name value = do
   value' <- lift $ getAttr props name
-  assertWarn ("field "<>name<>" has unexpected value "<>showAeson value'
-              <>", should be "<>showAeson value)
+  assertWarn ("field "<>name<>" has unexpected value "<>prettyprint value'
+              <>", should be "<>prettyprint value)
     $ value' == value
diff --git a/lib/Util.hs b/lib/Util.hs
index be67143..3a0e1d4 100644
--- a/lib/Util.hs
+++ b/lib/Util.hs
@@ -1,27 +1,37 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE LambdaCase        #-}
 {-# LANGUAGE OverloadedStrings #-}
 
-
+-- | has (perhaps inevitably) morphed into a module that mostly
+-- concerns itself with wrangling haskell's string types
 module Util where
 
-import Data.Text (Text)
-import Data.Text as T
-import Data.Aeson as Aeson
+import           Data.Aeson as Aeson
+import           Data.Text  (Text)
+import           Data.Text  as T
 
 -- | haskell's many string types are FUN …
 showText :: Show a => a -> Text
 showText = T.pack . show
 
--- | same as showText, but without the "String"-prefix for strings
--- TODO: serialise back into json for printing? People may get
--- confused by the type annotations if they only know json …
-showAeson :: Aeson.Value -> Text
-showAeson (Aeson.String s) = showText s
-showAeson v = showText v
-
+-- | a class to address all the string conversions necessary
+-- when using Show to much that just uses Text instead
+class PrettyPrint a where
+  prettyprint :: a -> Text
 
+-- | let's see if this is a good idea or makes type inference bite us
+instance PrettyPrint Text where
+  prettyprint text = "\"" <> text <> "\""
 
+-- | same as show json, but without the "String" prefix for json strings
+instance PrettyPrint Aeson.Value where
+  prettyprint = \case
+    Aeson.String s -> prettyprint s
+    v              -> (T.pack . show) v
 
+-- | here since Unit is sometimes used as dummy type
+instance PrettyPrint () where
+  prettyprint _ = error "shouldn't pretty-print Unit"
 
--- | adds quotes (but does not escape, for now!)
-quote :: Text -> Text
-quote text = "\"" <> text <> "\""
+printPretty :: PrettyPrint a => a -> IO ()
+printPretty = putStr . T.unpack . prettyprint