feat(users/Profpatsch): init whatcd-resolver r/6413

Change-Id: Ieb377fb8caa60e716703153dfeca5173f9a6779d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8830
Reviewed-by: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI

1 files changed, 15 insertions, 0 deletions

diff --git a/users/Profpatsch/whatcd-resolver/src/ValidationParseT.hs b/users/Profpatsch/whatcd-resolver/src/ValidationParseT.hs
new file mode 100644
index 000000000000..62322a0ac0bc
--- /dev/null
+++ b/users/Profpatsch/whatcd-resolver/src/ValidationParseT.hs
@@ -0,0 +1,15 @@
+module ValidationParseT where
+
+import Data.Functor.Compose (Compose (..))
+import PossehlAnalyticsPrelude
+
+-- | A simple way to create an Applicative parser that parses from some environment.
+--
+-- Use with DerivingVia. Grep codebase for examples.
+newtype ValidationParseT env m a = ValidationParseT {unValidationParseT :: env -> m (Validation (NonEmpty Error) a)}
+  deriving
+    (Functor, Applicative)
+    via ( Compose
+            ((->) env)
+            (Compose m (Validation (NonEmpty Error)))
+        )