Add accessDeniedWhen

My brain can't work with the double negative of `accessDeniedUnless`. It's much easier for me to say when to  access deny.

IHP/AuthSupport/Authorization.hs

@@ -10,16 +10,31 @@ import IHP.Prelude
 class CanView user model where
     canView :: (?modelContext :: ModelContext) => model -> user -> IO Bool
 
--- | Stops the action execution with an error message when the access condition is false.
+-- | Stops the action execution with an error message when the access condition is True.
 --
--- __Example:__ Checking a user is author of a blog post.
+-- __Example:__ Checking a user is the author of a blog post.
+-- 
+-- > action EditPostAction { postId } = do
+-- >     post <- fetch postId
+-- >     accessDeniedWhen (post.authorId /= currentUserId)
+-- >     
+-- >     renderHtml EditView { .. }
+--
+-- This will throw an error and prevent the view from being rendered when the current user is not the author of the post.
+accessDeniedWhen :: Bool -> IO ()
+accessDeniedWhen condition = if condition then fail "Access denied" else pure ()
+
+-- | Stops the action execution with an error message when the access condition is False.
+--
+-- __Example:__ Checking a user is the author of a blog post.
 -- 
 -- > action EditPostAction { postId } = do
 -- >     post <- fetch postId
 -- >     accessDeniedUnless (post.authorId == currentUserId)
 -- >     
 -- >     renderHtml EditView { .. }
 --
--- This will throw an error and prevent the view from being rendered when the current user is not author of the post.
+-- This will throw an error and prevent the view from being rendered when the current user is not the author of the post.
 accessDeniedUnless :: Bool -> IO ()
-accessDeniedUnless condition = if condition then pure () else fail "Access denied"
+accessDeniedUnless condition = if condition then pure () else fail "Access denied"
+