fix: dynamic test is green, but without mutations

Author: euonymos

example/CEM/Example/Auction.hs

@@ -133,12 +133,23 @@ instance CEMScript SimpleAuction where
                     )
                     cEmptyValue
                 )
-            , output
-                (userUtxo ctxParams.seller)
-                (cMinLovelace @<> cMkAdaOnlyValue buyoutBid.betAmount)
-            , output
-                (userUtxo buyoutBid.better)
-                (cMinLovelace @<> ctxParams.lot)
+            , if'
+                (ctxParams.seller `eq'` buyoutBid.better)
+                ( output
+                    (userUtxo ctxParams.seller)
+                    (cMinLovelace @<> ctxParams.lot)
+                )
+                ( output
+                    (userUtxo buyoutBid.better)
+                    (cMinLovelace @<> ctxParams.lot)
+                )
+            , if'
+                (ctxParams.seller `eq'` buyoutBid.better)
+                noop
+                ( output
+                    (userUtxo ctxParams.seller)
+                    (cMinLovelace @<> cMkAdaOnlyValue buyoutBid.betAmount)
+                )
             ]
           )
         ]

src/Cardano/CEM/DSL.hs

@@ -298,7 +298,7 @@ getMainSigner cs = case mapMaybe f cs of
   [pkh] -> pkh
   _ ->
     error
-      "Transition should have exactly one MainSignerCoinSelection constraint"
+      "Transition should have exactly one MainSigner* constraint"
   where
     f (MainSignerNoValue pkh) = Just pkh
     f (MainSignerCoinSelect pkh _ _) = Just pkh

src/Cardano/CEM/Smart.hs

@@ -19,8 +19,8 @@ import Plutarch.Prelude (
   (#&&),
  )
 import PlutusLedgerApi.V2 (PubKeyHash, ToData (..), Value)
-import Prelude hiding (error)
-import Prelude qualified (error)
+import Prelude hiding (Eq, error)
+import Prelude qualified (Eq, error)
 
 -- -----------------------------------------------------------------------------
 -- Helpers to be used in actual definitions
@@ -118,7 +118,7 @@ inState ::
 inState spine = UnsafeUpdateOfSpine ctxState spine []
 
 (@==) ::
-  (Eq x) => ConstraintDSL script x -> ConstraintDSL script x -> ConstraintDSL script Bool
+  (Prelude.Eq x) => ConstraintDSL script x -> ConstraintDSL script x -> ConstraintDSL script Bool
 (@==) = Eq
 
 (@<=) ::
@@ -254,3 +254,19 @@ match ::
   Map (Spine datatype) (TxConstraint resolved script) ->
   TxConstraint resolved script
 match = MatchBySpine
+
+if' ::
+  forall (resolved :: Bool) script.
+  DSLPattern resolved script Bool ->
+  TxConstraint resolved script ->
+  TxConstraint resolved script ->
+  TxConstraint resolved script
+if' = If
+
+eq' ::
+  forall x script.
+  (Prelude.Eq x) =>
+  ConstraintDSL script x ->
+  ConstraintDSL script x ->
+  ConstraintDSL script Bool
+eq' = Eq