From 307919760c58e037ec3260fcd0c3c7f7227fd7aa Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Mon, 26 Feb 2024 22:59:54 +0100
Subject: WIP typecheck and other stuff

---
 src/Data/Bag.hs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 src/Data/Bag.hs

(limited to 'src/Data/Bag.hs')

diff --git a/src/Data/Bag.hs b/src/Data/Bag.hs
new file mode 100644
index 0000000..9cdce89
--- /dev/null
+++ b/src/Data/Bag.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE DeriveTraversable #-}
+module Data.Bag where
+
+
+data Bag a
+  = BTwo (Bag a) (Bag a)
+  | BOne a
+  | BZero
+  deriving (Functor, Foldable, Traversable)
+
+instance Semigroup (Bag a) where (<>) = BTwo
+instance Monoid (Bag a) where mempty = BZero
+
+instance Applicative Bag where
+  pure = BOne
+
+  BZero <*> _ = BZero
+  _ <*> BZero = BZero
+  BOne f <*> b = f <$> b
+  BTwo b1 b2 <*> b = BTwo (b1 <*> b) (b2 <*> b)
-- 
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