Create data-backed types: List, Pair, Map

Signed-off-by: Ana Pantilie <ana.pantilie95@gmail.com>

plutus-tx/plutus-tx.cabal

@@ -73,6 +73,8 @@ library
     PlutusTx.Code
     PlutusTx.Coverage
     PlutusTx.DataList
+    PlutusTx.DataMap
+    PlutusTx.DataPair
     PlutusTx.Either
     PlutusTx.Enum
     PlutusTx.Eq

plutus-tx/src/PlutusTx/DataList.hs

@@ -6,15 +6,11 @@
 {-# LANGUAGE TypeFamilies       #-}
 {-# LANGUAGE ViewPatterns       #-}
 
-module PlutusTx.DataList (
-
-) where
+module PlutusTx.DataList where
 
 import PlutusTx.AsData qualified as AsData
 import PlutusTx.IsData qualified as P
-import PlutusTx.Prelude hiding (map)
-
-import GHC.Exts qualified as H
+import PlutusTx.Prelude qualified as Prelude
 
 AsData.asData
   [d|
@@ -24,36 +20,12 @@ AsData.asData
 
 type DataElem a = (P.UnsafeFromData a, P.ToData a)
 
-instance (DataElem a) => H.IsList (List a) where
-    type Item (List a) = a
-    fromList [] = Nil
-    fromList (x : xs) =
-      Cons x (H.fromList xs)
-    toList Nil         = []
-    toList (Cons x xs) = x : H.toList xs
-
-(.:) :: (DataElem a) => a -> List a -> List a
-(.:) = Cons
-
--- empty List is overloaded as []
-
--- examples of using overloaded syntax
-
-example0 :: DataElem a => List a
-example0 = []
-
-example1 :: List Bool
-example1 = [True, False]
-
-example2 :: List Integer
-example2 = [1..10]
+fromList :: DataElem a => [a] -> List a
+fromList = Prelude.foldr Cons Nil
 
--- examples of using overloaded pattern matching
-isSingleton :: DataElem a => List a -> Bool
-isSingleton [_] = True
-isSingleton _   = False
+foldr :: DataElem a => (a -> b -> b) -> b -> List a -> b
+foldr _ u Nil         = u
+foldr f u (Cons x xs) = f x (foldr f u xs)
 
-map :: (DataElem a, DataElem b) => (a -> b) -> List a -> List b
-map _ []                   = []
--- unfortunately matching on ':' doesn't work
-map f (H.toList -> x : xs) = f x .: map f (H.fromList xs)
+toList :: DataElem a => List a -> [a]
+toList = foldr (:) []

plutus-tx/src/PlutusTx/DataMap.hs

@@ -0,0 +1,17 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE PatternSynonyms    #-}
+{-# LANGUAGE TemplateHaskell    #-}
+{-# LANGUAGE ViewPatterns       #-}
+
+module PlutusTx.DataMap where
+
+import PlutusTx.AsData qualified as AsData
+import PlutusTx.DataList
+import PlutusTx.DataPair
+import PlutusTx.IsData qualified as P
+
+AsData.asData
+  [d|
+    data Map k v = Map (List (Pair k v))
+      deriving newtype (P.ToData, P.FromData, P.UnsafeFromData)
+  |]

plutus-tx/src/PlutusTx/DataPair.hs

@@ -0,0 +1,16 @@
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE PatternSynonyms    #-}
+{-# LANGUAGE TemplateHaskell    #-}
+{-# LANGUAGE ViewPatterns       #-}
+
+module PlutusTx.DataPair where
+
+import PlutusTx.AsData qualified as AsData
+import PlutusTx.IsData qualified as P
+import PlutusTx.Prelude qualified as Prelude
+
+AsData.asData
+  [d|
+    data Pair a b = Pair a b
+      deriving newtype (P.ToData, P.FromData, P.UnsafeFromData)
+  |]