Provide more building blocks and extend example

byg/src/ComputationM.hs

@@ -2,6 +2,8 @@
 module ComputationM
   ( ComputationM
   , Token
+  , tupleTokens
+  , zipTokens
   , evalComputationM
   , inject
   , mapComputationM
@@ -30,10 +32,17 @@ deriving instance (Show a, Show b) => Show (TypedRun a b)
 data Token a where
   Token :: Int -> Token a
   TupleToken :: Token a -> Token b -> Token (a, b)
+  ZipToken :: Token [a] -> Token [b] -> Token [(a, b)]
   NoToken :: Token ()
 
 deriving instance Show (Token a)
 
+tupleTokens :: (Show a, Show b) => Token a -> Token b -> Token (a, b)
+tupleTokens = TupleToken
+
+zipTokens :: (Show a, Show b) => Token [a] -> Token [b] -> Token [(a, b)]
+zipTokens = ZipToken
+
 data Dependency a b = Dependency (Token a) (TypedRun a b) (Token b)
   deriving (Show)