diff --git a/CHANGELOG.md b/CHANGELOG.md
index c1e1b98..d8e5444 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,5 @@
+# 0.2.0 - UNRELEASED
+
 # 0.1.2 - **Critical fix** for `PlyArg Credential` instance
 
 - The instance was buggy and did not produce proper UPLC. Any types containing `Credential` (e.g `Address`) may have been affected.
diff --git a/ply-core/ply-core.cabal b/ply-core/ply-core.cabal
index c342135..e5d1f64 100644
--- a/ply-core/ply-core.cabal
+++ b/ply-core/ply-core.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name:          ply-core
-version:       0.1.2
+version:       0.2.0
 author:        Chase <chase@mlabs.city>
 license:       MIT
 
@@ -127,6 +127,10 @@ test-suite ply-core-test
   import:         common-ghc-opts
   type:           exitcode-stdio-1.0
   main-is:        Spec.hs
-  build-depends:  ply-core
+  build-depends:
+    , ply-core
+    , tasty
+    , tasty-quickcheck
+
   hs-source-dirs: test
   ghc-options:    -threaded -rtsopts -with-rtsopts=-N
diff --git a/ply-core/src/Ply/Core/Class.hs b/ply-core/src/Ply/Core/Class.hs
index a559db4..072c004 100644
--- a/ply-core/src/Ply/Core/Class.hs
+++ b/ply-core/src/Ply/Core/Class.hs
@@ -1,16 +1,21 @@
+{-# LANGUAGE DefaultSignatures #-}
 {-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE UndecidableSuperClasses #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 
-module Ply.Core.Class (PlyArg (UPLCRep, ToDataConstraint, toBuiltinArg, toBuiltinArgData), someBuiltinArg) where
+module Ply.Core.Class (
+  PlyArg (UPLCRep, toBuiltinArg),
+  PlyArgData (toBuiltinArgData),
+  someBuiltinArg,
+  someBuiltinArgData,
+) where
 
 import Data.Bifunctor (Bifunctor (bimap), second)
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as BS
-import Data.Kind (Constraint, Type)
+import Data.Kind (Type)
 import qualified Data.Map.Strict as M
 import Data.Text (Text)
-import GHC.TypeLits (ErrorMessage (ShowType, Text))
 
 import PlutusCore (DefaultUni, Includes, Some, ValueOf)
 import qualified PlutusCore as PLC
@@ -19,8 +24,6 @@ import qualified PlutusTx.AssocMap as PlutusMap
 import Ply.LedgerExports.Common
 import qualified Ply.LedgerExports.V1 as LedgerV1
 
-type BottomConstraint s t = 'Text s ~ ShowType t
-
 {- | Class of haskell types that can be applied as arguments to a Plutus script.
 
 This class is meant to not only convert a type to its UPLC builtin representation, but _also verify_ any
@@ -30,89 +33,110 @@ As a result, 'toBuiltinArg' is partial for types that don't hold their invariant
 
 == Laws
 
- 1. If 'toBuiltinArg'/'toBuiltinArgData' is applied over `x`, all contained 'PlyArg's within should also have
- their corresponding 'toBuiltinArg'/'toBuiltinArgData' applied over them.
-
- 2. If @UPLCRep a = Data@; @toBuiltinArgData = toBuiltinArg@
+ 1. If 'toBuiltinArg' is applied over `x`, all contained 'PlyArg's within should also have
+ their corresponding 'toBuiltinArg' applied over them.
 
- 3. Assuming a lawful 'Eq' instance (i.e the 'Eq' instance is aware of any invariants):
-    @fromData (toBuiltinArgData x) == Just x@
+ 2. Assuming a lawful 'Eq' instance (i.e the 'Eq' instance is aware of any invariants):
+    @fromBuiltin' (toBuiltinArg x) == x@
 
- 4. 'toBuiltinArgData' implementation must perform the same validations/normalizations as 'toBuiltinArg'.
+    Where `fromBuiltin'` is capable of parsing the _correct_ UPLC representation of a type into the type itself.
 -}
 class DefaultUni `Includes` UPLCRep a => PlyArg a where
   type UPLCRep a :: Type
-  type ToDataConstraint a :: Constraint
-  type ToDataConstraint a = ()
   toBuiltinArg :: a -> UPLCRep a
-  toBuiltinArgData :: ToDataConstraint a => a -> Data
+
+{- | Class of haskell types that can be applied as data encoded arguments to a Plutus script.
+
+Similar to 'PlyArg', this class should also verify the same invariants for each type.
+
+If 'UPLCRep a ~ Data', this instance is free and does not need any explicit method definition.
+
+== Laws
+
+ 1. If @UPLCRep a = Data@; @toBuiltinArgData = toBuiltinArg@
+
+    Otherwise: @toBuiltinArgData = toData . toBuiltinArg@
+
+    (assume 'toData @ByteString' simply delegates to 'toData @BuiltinByteString')
+
+ 2. Assuming a lawful 'Eq' instance (i.e the 'Eq' instance is aware of any invariants):
+    @fromData (toBuiltinArgData x) == Just x@
+-}
+class PlyArg a => PlyArgData a where
+  toBuiltinArgData :: a -> Data
+  default toBuiltinArgData :: UPLCRep a ~ Data => a -> Data
+  toBuiltinArgData = toBuiltinArg
 
 -- | Create a PlutusCore 'Some' value from a 'PlyArg'.
 someBuiltinArg :: PlyArg a => a -> Some (ValueOf DefaultUni)
 someBuiltinArg = PLC.someValue . toBuiltinArg
 
+-- | Create a PlutusCore 'Some' data value from a 'PlyArg'.
+someBuiltinArgData :: PlyArgData a => a -> Some (ValueOf DefaultUni)
+someBuiltinArgData = PLC.someValue . toBuiltinArgData
+
 instance PlyArg Bool where
   type UPLCRep Bool = Bool
   toBuiltinArg = id
+instance PlyArgData Bool where
   toBuiltinArgData = toData
 
 instance PlyArg Integer where
   type UPLCRep Integer = Integer
   toBuiltinArg = id
+instance PlyArgData Integer where
   toBuiltinArgData = toData
 
 instance PlyArg () where
   type UPLCRep () = ()
   toBuiltinArg = id
+instance PlyArgData () where
   toBuiltinArgData = toData
 
 instance PlyArg BuiltinByteString where
   type UPLCRep BuiltinByteString = ByteString
   toBuiltinArg = fromBuiltin
+instance PlyArgData BuiltinByteString where
   toBuiltinArgData = toData
 
 instance PlyArg ByteString where
   type UPLCRep ByteString = ByteString
   toBuiltinArg = id
+instance PlyArgData ByteString where
   toBuiltinArgData = toData . toBuiltin
 
--- | 'toBuiltinArgData' is uncallable for this instance.
 instance PlyArg Text where
   type UPLCRep Text = Text
-  type ToDataConstraint Text = BottomConstraint "toBuiltinArgData(Text): unsupported" Text
   toBuiltinArg = id
-  toBuiltinArgData = error "toBuiltinArgData(Text): uncallable function was called"
 
 instance PlyArg Data where
   type UPLCRep Data = Data
   toBuiltinArg = id
-  toBuiltinArgData = id
+instance PlyArgData Data
 
 instance (PlyArg a, PlyArg b) => PlyArg (a, b) where
   type UPLCRep (a, b) = (UPLCRep a, UPLCRep b)
-  type ToDataConstraint (a, b) = (ToDataConstraint a, ToDataConstraint b)
   toBuiltinArg (x, y) = (toBuiltinArg x, toBuiltinArg y)
+instance (PlyArgData a, PlyArgData b) => PlyArgData (a, b) where
   toBuiltinArgData (x, y) = Constr 0 [toBuiltinArgData x, toBuiltinArgData y]
 
 instance PlyArg a => PlyArg [a] where
   type UPLCRep [a] = [UPLCRep a]
-  type ToDataConstraint [a] = ToDataConstraint a
   toBuiltinArg = map toBuiltinArg
+instance PlyArgData a => PlyArgData [a] where
   toBuiltinArgData l = List $ map toBuiltinArgData l
 
-instance (PlyArg a, ToDataConstraint a) => PlyArg (Maybe a) where
+instance PlyArgData a => PlyArg (Maybe a) where
   type UPLCRep (Maybe a) = Data
   toBuiltinArg Nothing = Constr 1 []
   toBuiltinArg (Just x) = Constr 0 [toBuiltinArgData x]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData a => PlyArgData (Maybe a)
 
 -- | This instance sorts the map.
 instance
-  ( PlyArg k
-  , ToDataConstraint k
+  ( PlyArgData k
   , Ord k
-  , PlyArg v
-  , ToDataConstraint v
+  , PlyArgData v
   ) =>
   PlyArg (PlutusMap.Map k v)
   where
@@ -122,6 +146,14 @@ instance
       . M.toAscList
       . M.fromList
       . PlutusMap.toList
+
+instance
+  ( PlyArgData k
+  , Ord k
+  , PlyArgData v
+  ) =>
+  PlyArgData (PlutusMap.Map k v)
+  where
   toBuiltinArgData = Map . toBuiltinArg
 
 -- | This instance sorts the 'Value' and removes all zero entries.
@@ -144,6 +176,8 @@ instance PlyArg Value where
           . M.fromListWith (<>)
           . map (second (M.fromListWith (+) . PlutusMap.toList))
           $ PlutusMap.toList m
+
+instance PlyArgData Value where
   toBuiltinArgData = Map . toBuiltinArg
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
@@ -152,13 +186,14 @@ instance PlyArg Credential where
   toBuiltinArg cred = case cred of
     PubKeyCredential h -> Constr 0 [toBuiltinArgData h]
     ScriptCredential h -> Constr 1 [toBuiltinArgData h]
-  toBuiltinArgData = toBuiltinArg
+
+instance PlyArgData Credential
 
 instance PlyArg StakingCredential where
   type UPLCRep StakingCredential = Data
   toBuiltinArg (StakingHash cred) = Constr 0 [toBuiltinArg cred]
   toBuiltinArg x = toData x
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData StakingCredential
 
 instance PlyArg Address where
   type UPLCRep Address = Data
@@ -166,7 +201,7 @@ instance PlyArg Address where
     let credData = toBuiltinArg cred
         stakeCredData = toBuiltinArg stakeCred
      in Constr 0 [credData, stakeCredData]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData Address
 
 -- | This verifies the underlying bytestring is exactly 0 (for adaSymbol) or 28 bytes.
 instance PlyArg CurrencySymbol where
@@ -179,6 +214,8 @@ instance PlyArg CurrencySymbol where
         else error "toBuiltinArg(CurrencySymbol): Expected exactly 0 or 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData CurrencySymbol where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying bytestring is no longer than 32 bytes.
@@ -190,12 +227,14 @@ instance PlyArg TokenName where
       else error "toBuiltinArg(TokenName): Expected 32 bytes or less"
     where
       bs = fromBuiltin x
+
+instance PlyArgData TokenName where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 instance PlyArg AssetClass where
   type UPLCRep AssetClass = Data
   toBuiltinArg (AssetClass i) = toBuiltinArgData i
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData AssetClass
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
 instance PlyArg PubKeyHash where
@@ -206,6 +245,8 @@ instance PlyArg PubKeyHash where
       else error "toBuiltinArg(PubKeyHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData PubKeyHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying integer is non-negative.
@@ -215,6 +256,8 @@ instance PlyArg POSIXTime where
     if i >= 0
       then i
       else error "toBuiltinArg(POSIXTime): Expected non-negative"
+
+instance PlyArgData POSIXTime where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying integer is non-negative.
@@ -224,29 +267,28 @@ instance PlyArg DiffMilliSeconds where
     if i >= 0
       then i
       else error "toBuiltinArg(DiffMilliSeconds): Expected non-negative"
-  toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
-instance (PlyArg a, ToDataConstraint a) => PlyArg (Extended a) where
+instance PlyArgData a => PlyArg (Extended a) where
   type UPLCRep (Extended a) = Data
   toBuiltinArg NegInf = Constr 0 []
   toBuiltinArg (Finite a) = Constr 0 [toBuiltinArgData a]
   toBuiltinArg PosInf = Constr 1 []
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData a => PlyArgData (Extended a)
 
-instance (PlyArg a, ToDataConstraint a) => PlyArg (UpperBound a) where
+instance PlyArgData a => PlyArg (UpperBound a) where
   type UPLCRep (UpperBound a) = Data
   toBuiltinArg (UpperBound ext cls) = Constr 0 [toBuiltinArgData ext, toBuiltinArgData cls]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData a => PlyArgData (UpperBound a)
 
-instance (PlyArg a, ToDataConstraint a) => PlyArg (LowerBound a) where
+instance PlyArgData a => PlyArg (LowerBound a) where
   type UPLCRep (LowerBound a) = Data
   toBuiltinArg (LowerBound ext cls) = Constr 0 [toBuiltinArgData ext, toBuiltinArgData cls]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData a => PlyArgData (LowerBound a)
 
-instance (PlyArg a, ToDataConstraint a) => PlyArg (Interval a) where
+instance PlyArgData a => PlyArg (Interval a) where
   type UPLCRep (Interval a) = Data
   toBuiltinArg (Interval lb ub) = Constr 0 [toBuiltinArgData lb, toBuiltinArgData ub]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData a => PlyArgData (Interval a)
 
 instance PlyArg DCert where
   type UPLCRep DCert = Data
@@ -257,7 +299,7 @@ instance PlyArg DCert where
   toBuiltinArg (DCertPoolRetire pkh i) = Constr 4 [toBuiltinArgData pkh, toBuiltinArgData i]
   toBuiltinArg DCertGenesis = Constr 5 []
   toBuiltinArg DCertMir = Constr 6 []
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData DCert
 
 -- | This verifies the underlying bytestring is exactly 32 bytes.
 instance PlyArg TxId where
@@ -269,7 +311,8 @@ instance PlyArg TxId where
       else error "toBuiltinArg(TxId): Expected 32 bytes"
     where
       bs = fromBuiltin x
-  toBuiltinArgData = toBuiltinArgData . toBuiltinArg
+
+instance PlyArgData TxId
 
 -- | This verifies the txIdx is non-negative.
 instance PlyArg TxOutRef where
@@ -278,7 +321,8 @@ instance PlyArg TxOutRef where
     if txIdx >= 0
       then Constr 0 [toBuiltinArgData txId, toBuiltinArgData txIdx]
       else error "toBuiltinArg(TxOutRef): Expected non-negative idx"
-  toBuiltinArgData = toBuiltinArg
+
+instance PlyArgData TxOutRef
 
 instance PlyArg LedgerV1.TxOut where
   type UPLCRep LedgerV1.TxOut = Data
@@ -289,12 +333,12 @@ instance PlyArg LedgerV1.TxOut where
       , toBuiltinArgData val
       , toBuiltinArgData dh
       ]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData LedgerV1.TxOut
 
 instance PlyArg LedgerV1.TxInInfo where
   type UPLCRep LedgerV1.TxInInfo = Data
   toBuiltinArg (LedgerV1.TxInInfo ref out) = Constr 0 [toBuiltinArgData ref, toBuiltinArgData out]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData LedgerV1.TxInInfo
 
 instance PlyArg LedgerV1.TxInfo where
   type UPLCRep LedgerV1.TxInfo = Data
@@ -324,7 +368,7 @@ instance PlyArg LedgerV1.TxInfo where
         , toBuiltinArgData datumMap
         , toBuiltinArgData txId
         ]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData LedgerV1.TxInfo
 
 instance PlyArg ScriptPurpose where
   type UPLCRep ScriptPurpose = Data
@@ -332,22 +376,22 @@ instance PlyArg ScriptPurpose where
   toBuiltinArg (Spending ref) = Constr 1 [toBuiltinArgData ref]
   toBuiltinArg (Rewarding stakeCred) = Constr 2 [toBuiltinArgData stakeCred]
   toBuiltinArg (Certifying dcert) = Constr 3 [toBuiltinArgData dcert]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData ScriptPurpose
 
 instance PlyArg LedgerV1.ScriptContext where
   type UPLCRep LedgerV1.ScriptContext = Data
   toBuiltinArg (LedgerV1.ScriptContext inf purp) = Constr 0 [toBuiltinArgData inf, toBuiltinArgData purp]
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData LedgerV1.ScriptContext
 
 instance PlyArg Datum where
   type UPLCRep Datum = Data
   toBuiltinArg (Datum d) = toData d
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData Datum
 
 instance PlyArg Redeemer where
   type UPLCRep Redeemer = Data
   toBuiltinArg (Redeemer d) = toData d
-  toBuiltinArgData = toBuiltinArg
+instance PlyArgData Redeemer
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
 instance PlyArg ScriptHash where
@@ -358,6 +402,8 @@ instance PlyArg ScriptHash where
       else error "toBuiltinArg(ScriptHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData ScriptHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
@@ -369,6 +415,8 @@ instance PlyArg ValidatorHash where
       else error "toBuiltinArg(ValidatorHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData ValidatorHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
@@ -380,6 +428,8 @@ instance PlyArg MintingPolicyHash where
       else error "toBuiltinArg(MintingPolicyHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData MintingPolicyHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
@@ -391,6 +441,8 @@ instance PlyArg DatumHash where
       else error "toBuiltinArg(DatumHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData DatumHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
 
 -- | This verifies the underlying bytestring is exactly 28 bytes.
@@ -402,4 +454,6 @@ instance PlyArg RedeemerHash where
       else error "toBuiltinArg(RedeemerHash): Expected 28 bytes"
     where
       bs = fromBuiltin x
+
+instance PlyArgData RedeemerHash where
   toBuiltinArgData = toBuiltinArgData . toBuiltinArg
diff --git a/ply-plutarch/ply-plutarch.cabal b/ply-plutarch/ply-plutarch.cabal
index 19267f3..b5b9c15 100644
--- a/ply-plutarch/ply-plutarch.cabal
+++ b/ply-plutarch/ply-plutarch.cabal
@@ -1,6 +1,6 @@
 cabal-version: 3.0
 name:          ply-plutarch
-version:       0.1.2
+version:       0.2.0
 author:        Chase <chase@mlabs.city>
 license:       MIT
 
diff --git a/ply-plutarch/src/Ply/Plutarch/Class.hs b/ply-plutarch/src/Ply/Plutarch/Class.hs
index 967cd5b..68125cf 100644
--- a/ply-plutarch/src/Ply/Plutarch/Class.hs
+++ b/ply-plutarch/src/Ply/Plutarch/Class.hs
@@ -12,7 +12,14 @@ import qualified PlutusTx.AssocMap as PlutusMap
 
 -- TODO: How to handle 'PAsData'?
 
--- | 'PlyArgOf' yields the corresponding Haskell type for a given Plutarch type.
+{- | 'PlyArgOf' yields the corresponding Haskell type for a given Plutarch type.
+
+== Laws
+
+'PlyArgOf p' should be the _proper Haskell synonym_ of the Plutarch type p. Refer to
+the Plutarch docs, specifically 'PIsData' and 'PConstant'/'PLift', for information
+on type representation and correspondence.
+-}
 type PlyArgOf :: PType -> Type
 type family PlyArgOf a = r | r -> a