Empty the cache at start

guide.cabal

@@ -66,6 +66,7 @@ executable guide
                      , http-types
                      , ilist
                      , iproute == 1.7.*
+                     , list-t
                      , lucid >= 2.9.5 && < 3
                      , megaparsec == 4.4.*
                      , microlens-platform >= 0.3.2

src/Cache.hs

@@ -8,6 +8,7 @@ module Cache
 (
   CacheKey(..),
   invalidateCache,
+  emptyCache,
   cached,
 )
 where
@@ -25,6 +26,7 @@ import qualified Data.ByteString.Lazy as BSL
 -- Concurrent map
 import qualified STMContainers.Map as STMMap
 import Data.Hashable
+import qualified ListT
 -- Lucid
 import Lucid.Base
 
@@ -108,6 +110,12 @@ invalidateCache gs key = liftIO $ atomically $ do
   for_ (cacheDepends gs key) $ \k ->
     STMMap.delete k cache
 
+-- TODO: Should be easier once
+-- https://github.com/nikita-volkov/stm-containers/issues/6 is closed.
+emptyCache :: MonadIO m => m ()
+emptyCache = liftIO $ atomically $
+  ListT.traverse_ (\(k,_) -> STMMap.delete k cache) (STMMap.stream cache)
+
 cached :: MonadIO m => CacheKey -> HtmlT m () -> HtmlT m ()
 cached key gen = do
   mbRes <- liftIO . atomically $ STMMap.lookup key cache

src/Main.hs

@@ -719,6 +719,10 @@ createCheckpoint' db = liftIO $ do
 
 main :: IO ()
 main = do
+  -- Emptying the cache is needed because during development (i.e. in REPL)
+  -- 'main' can be started many times and if the cache isn't cleared changes
+  -- won't be visible
+  emptyCache
   config <- readConfig
   let emptyState = GlobalState {
         _categories = [],