first example of a map adjustment

this also includes some more monad plumbing, and an option for the
linter to actually write things out again. Some of the previous commit
was reverted a bit since it turned out to be stupid, but overall it was
suprisingly easy once I got around to it, so yay! i guess

Also includes a fairly silly example of how to use it.

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/Tiled2.hs b/lib/Tiled2.hs
index a82de2c..e281d00 100644
--- a/lib/Tiled2.hs
+++ b/lib/Tiled2.hs
@@ -24,9 +24,11 @@ import qualified Data.ByteString.Lazy   as LB
 import           Data.Char              (toLower)
 import           Data.Map               (Map)
 import           Data.Maybe             (fromMaybe)
+import           Data.String            (IsString (fromString))
 import           Data.Text              (Text)
+import qualified Data.Text              as T
 import           Data.Vector            (Vector)
-import           GHC.Exts               (fromList, toList)
+import           GHC.Exts               (IsString, fromList, toList)
 import           GHC.Generics           (Generic)
 
 
@@ -89,6 +91,8 @@ data PropertyValue = StrProp Text | BoolProp Bool
 data Property = Property Text PropertyValue
   deriving (Eq, Generic, Show)
 
+instance IsString PropertyValue where
+  fromString s = StrProp (T.pack s)
 
 instance FromJSON Property where
   parseJSON (A.Object o) = do
@@ -343,12 +347,17 @@ instance ToJSON Tiledmap where
 
 class HasProperties a where
   getProperties :: a -> [Property]
+  adjustProperties :: ([Property] -> Maybe [Property]) -> a -> a
 
 instance HasProperties Layer where
   getProperties = fromMaybe [] . layerProperties
+  adjustProperties f layer = layer
+    { layerProperties = f (getProperties layer) }
 
 instance HasProperties Tileset where
   getProperties = fromMaybe [] . tilesetProperties
+  adjustProperties f tileset = tileset
+    { tilesetProperties = f (getProperties tileset) }
 
 class HasName a where
   getName :: a -> Text