Add useStateEq' hook

src/Yoga/Block/Hook/UseStateEq.purs

@@ -0,0 +1,29 @@
+module Yoga.Block.Hook.UseStateEq where
+
+import Prelude
+
+import Data.Newtype (class Newtype)
+import Data.Tuple.Nested (type (/\), (/\))
+import Effect (Effect)
+import React.Basic.Hooks (UseState, Hook, coerceHook)
+import React.Basic.Hooks as React
+
+newtype UseStateEq a hooks = UseStateEq (UseState a hooks)
+
+derive instance Newtype (UseStateEq a hooks) _
+
+-- [TODO] I'm too stupid to write this
+-- useStateEq :: forall a. Eq a => a -> Hook (UseStateEq a) (a /\ ((a -> a) -> Effect Unit))
+-- useStateEq initialValue = coerceHook React.do
+--   value /\ update <- React.useState initialValue
+--   let
+--     updateEq modify = do
+--       modified <- modify value
+--       when (modified /= value) do update (const modified)
+--   pure (value /\ updateEq)
+
+useStateEq' :: forall a. Eq a => a -> Hook (UseStateEq a) (a /\ (a -> Effect Unit))
+useStateEq' initialValue = coerceHook React.do
+  value /\ setValue <- React.useState' initialValue
+  let updateEq newValue = do when (newValue /= value) do setValue newValue
+  pure (value /\ updateEq)