fix: ParRes with no children converted to Null log (#699)

model/inline/src/main/scala/aqua/model/inline/Inline.scala

@@ -1,6 +1,6 @@
 package aqua.model.inline
 
-import aqua.model.{OpModel, ParModel, SeqModel}
+import aqua.model.{EmptyModel, OpModel, ParModel, SeqModel}
 import aqua.raw.ops.RawTag
 import aqua.raw.value.ValueRaw
 import cats.Monoid
@@ -33,7 +33,10 @@ private[inline] case class Inline(
         case l =>
           mergeMode match
             case SeqMode =>
-              Chain.one(SeqModel.wrap(l: _*))
+              val wrapped = SeqModel.wrap(l: _*)
+              wrapped match
+                case EmptyModel.leaf => Chain.empty
+                case _ => Chain.one(wrapped)
             case ParMode => Chain.one(ParModel.wrap(l: _*))
       }
 

model/inline/src/main/scala/aqua/model/inline/RawValueInliner.scala

@@ -107,7 +107,7 @@ object RawValueInliner extends Logging {
       ops <- inlineToTree(map)
       _ = logger.trace("desugarized ops: " + ops)
       _ = logger.trace("map was: " + map)
-    } yield vm -> parDesugarPrefix(ops)
+    } yield vm -> parDesugarPrefix(ops.filterNot(_ == EmptyModel.leaf))
 
   def collectionToModel[S: Mangler: Exports: Arrows](
     value: CollectionRaw,

model/inline/src/main/scala/aqua/model/inline/TagInliner.scala

@@ -35,6 +35,16 @@ object TagInliner extends Logging {
   private def none[S]: State[S, (Option[OpModel], Option[OpModel.Tree])] =
     State.pure(None -> None)
 
+  private def combineOpsWithSeq(l: Option[OpModel.Tree], r: Option[OpModel.Tree]) =
+    l match {
+      case None => r
+      case Some(a) =>
+        r match {
+          case None => l
+          case Some(b) => Some(SeqModel.wrap(a, b))
+        }
+    }
+
   def canonicalizeIfStream[S: Mangler](
     vm: ValueModel,
     ops: Option[OpModel.Tree]
@@ -45,7 +55,7 @@ object TagInliner extends Logging {
         Mangler[S].findAndForbidName(canonName).map { n =>
           val canon = VarModel(n, CanonStreamType(el), l)
           val canonModel = CanonicalizeModel(vm, CallModel.Export(canon.name, canon.`type`)).leaf
-          canon -> Some(ops.fold(canonModel)(t => SeqModel.wrap(t, canonModel)))
+          canon -> combineOpsWithSeq(ops, Option(canonModel))
         }
       case _ => State.pure(vm -> ops)
     }
@@ -69,7 +79,7 @@ object TagInliner extends Logging {
           flatResult <- flatCanonStream(canonV, Some(canonOp))
         } yield {
           val (resV, resOp) = flatResult
-          (resV, op.fold(resOp)(t => resOp.map(o => SeqModel.wrap(t, o))))
+          (resV, combineOpsWithSeq(op, resOp))
         }
       case v @ VarModel(_, CanonStreamType(_), _) =>
         flatCanonStream(v, op)
@@ -88,7 +98,7 @@ object TagInliner extends Logging {
         val apOp = FlattenModel(canonV, apN).leaf
         (
           apV,
-          Some(op.fold(apOp)(o => SeqModel.wrap(o, apOp)))
+          combineOpsWithSeq(op, Option(apOp))
         )
       }
     } else {
@@ -171,7 +181,7 @@ object TagInliner extends Logging {
           case (l @ LiteralModel(_, _), p) =>
             for {
               _ <- Exports[S].resolved(exportTo.name, l)
-            } yield Some(SeqModel) -> p
+            } yield None -> p
           case (v, p) =>
             State.pure(Some(CanonicalizeModel(v, CallModel.callExport(exportTo))) -> p)
         }
@@ -182,7 +192,7 @@ object TagInliner extends Logging {
           case (l @ LiteralModel(_, _), p) =>
             for {
               _ <- Exports[S].resolved(assignTo, l)
-            } yield Some(SeqModel) -> p
+            } yield None -> p
           case (v, p) =>
             State.pure(Some(FlattenModel(v, assignTo)) -> p)
         }
@@ -211,7 +221,7 @@ object TagInliner extends Logging {
         }).flatMap { cd =>
           for {
             _ <- Exports[S].resolved(assignTo, cd._1)
-          } yield Some(SeqModel) -> cd._2
+          } yield None -> cd._2
         }
 
       case ClosureTag(arrow, detach) =>

model/inline/src/test/scala/aqua/model/inline/RawValueInlinerSpec.scala

@@ -134,7 +134,7 @@ class RawValueInlinerSpec extends AnyFlatSpec with Matchers {
         "x",
         ArrayType(ScalarType.string),
         Chain.one(IntoIndexModel("y", ScalarType.string))
-      ) -> Some(EmptyModel.leaf)
+      ) -> None
     )
   }
 

model/inline/src/test/scala/aqua/model/inline/TagInlinerSpec.scala

@@ -23,7 +23,7 @@ class TagInlinerSpec extends AnyFlatSpec with Matchers {
       .value
 
     model._1.resolvedExports(canonTo) shouldBe LiteralModel(ValueRaw.Nil.value, ValueRaw.Nil.baseType)
-    model._2._1 shouldBe Some(SeqModel)
+    model._2._1 shouldBe None
     model._2._2 shouldBe None
   }
 
@@ -42,7 +42,7 @@ class TagInlinerSpec extends AnyFlatSpec with Matchers {
       ValueRaw.Nil.value,
       ValueRaw.Nil.baseType
     )
-    model._2._1 shouldBe Some(SeqModel)
+    model._2._1 shouldBe None
     model._2._2 shouldBe None
   }
 }

model/res/src/main/scala/aqua/res/MakeRes.scala

@@ -57,7 +57,8 @@ object MakeRes {
       MatchMismatchRes(a, b, s).leaf
     case ForModel(item, iter, mode) if !isNillLiteral(iter) => FoldRes(item, iter, mode).leaf
     case RestrictionModel(item, isStream) => RestrictionRes(item, isStream).leaf
-    case ParModel | DetachModel => ParRes.leaf
+    case DetachModel => ParRes.leaf
+    case ParModel => ParRes.leaf
     case XorModel => XorRes.leaf
     case NextModel(item) => NextRes(item).leaf
     case PushToStreamModel(operand @ VarModel(_, StreamType(st), _), exportTo) =>