1 files changed, 20 insertions, 0 deletions
diff --git a/src/HStyle/Checker.hs b/src/HStyle/Checker.hs
new file mode 100644
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--- /dev/null
+++ b/src/HStyle/Checker.hs
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+module HStyle.Checker
+    ( Checker
+    , checkLines
+    ) where
+
+import Data.Text (Text)
+
+import HStyle.Block
+
+-- | Takes a number of lines, and notifies of problems on each line. Indices
+-- in the result are 1-based.
+type Checker = Block -> [(Int, Text)]
+
+-- | Check every line of the block, possibly returning a problem description
+checkLines :: (Text -> Maybe Text) -> Checker
+checkLines checker block = do
+    (ln, text) <- zip [1 ..] (toLines block)
+    case checker text of
+        Nothing -> []
+        Just p  -> [(ln , p)]