add scalafmt, use only one nil

.scalafmt.conf

@@ -62,9 +62,9 @@ runner {
   }
 }
 
-rewrite {
-  rules = [
-    SortImports
-  ]
-}
+rewrite.rules = [Imports]
+rewrite.imports.sort = ascii
+rewrite.imports.groups = [
+  ["aqua\\..*"]
+]
 #runner.dialect = scala3

model/raw/src/main/scala/aqua/raw/value/ValueRaw.scala

@@ -34,7 +34,6 @@ object ValueRaw {
   val ParticleTimestamp: LiteralRaw = LiteralRaw("%timestamp%", ScalarType.u64)
 
   val Nil: LiteralRaw = LiteralRaw("[]", StreamType(BottomType))
-  val VarNil: VarRaw = VarRaw("nil", StreamType(BottomType))
 
   /**
    * Type of error value

semantics/src/main/scala/aqua/semantics/rules/ValuesAlgebra.scala

@@ -78,6 +78,9 @@ class ValuesAlgebra[S[_], Alg[_]: Monad](using
       case l @ LiteralToken(_, t) =>
         LiteralRaw(l.value, t).some.pure[Alg]
 
+      case VarToken(name) if name.value == ValueRaw.Nil.value =>
+        ValueRaw.Nil.some.pure[Alg]
+
       case VarToken(name) =>
         N.read(name, mustBeDefined = false).flatMap {
           case Some(t) =>

semantics/src/main/scala/aqua/semantics/rules/names/NamesInterpreter.scala

@@ -134,7 +134,7 @@ class NamesInterpreter[S[_], X](using
 
   override def assign(name: Name[S], value: ValueRaw): SX[Boolean] =
     value match {
-      case ValueRaw.Nil | ValueRaw.VarNil =>
+      case ValueRaw.Nil =>
         report
           .error(
             name,

semantics/src/test/scala/aqua/semantics/AssignmentSemSpec.scala

@@ -15,7 +15,7 @@ import org.scalatest.matchers.should.Matchers
 
 class AssignmentSemSpec extends AnyFlatSpec with Matchers with Inside {
 
-  import Utils.{*, given}
+  import Utils.{given, *}
 
   val program: Prog[State[CompilerState[cats.Id], *], Raw] = {
     val expr = ClosureExpr(Name[Id]("closure"), None)