From 99f6d8c0e4e5cdf0f5b91a5d6a39977639abc57e Mon Sep 17 00:00:00 2001
From: Mateusz Kowalewski <7350866+MateuszKowalewski@users.noreply.github.com>
Date: Sun, 2 Jul 2023 17:55:44 +0200
Subject: [PATCH] Introduce warning supression for problematic pattern-matches

This is a temporary workaround. The long term goal is to get rid
of these nasty annotations again. This will need support form the
Scala team though.
---
 core/src/main/scala/libretto/CoreLib.scala    |  7 +++
 core/src/main/scala/libretto/InvertLib.scala  |  2 +
 .../scala/libretto/scaletto/ScalettoLib.scala |  2 +
 .../impl/futurebased/FutureExecutor.scala     |  2 +
 .../unaryArithmetic/package.scala             |  2 +
 .../SunflowerProcessingFacility.scala         |  2 +
 .../src/main/scala/libretto/lambda/Bin.scala  |  4 ++
 .../main/scala/libretto/lambda/Lambdas.scala  |  2 +
 .../scala/libretto/lambda/LambdasImpl.scala   | 13 ++++++
 .../scala/libretto/lambda/Projection.scala    |  3 ++
 .../main/scala/libretto/lambda/Shuffle.scala  | 45 +++++++++++++++++--
 .../main/scala/libretto/lambda/Shuffled.scala |  9 ++++
 .../src/test/scala/libretto/lambda/Fun.scala  |  2 +
 .../scala/libretto/stream/CoreStreams.scala   |  4 ++
 .../stream/scaletto/ScalettoStreams.scala     |  3 ++
 .../scaletto/ScalettoTestExecutor.scala       |  2 +
 16 files changed, 101 insertions(+), 3 deletions(-)

diff --git a/core/src/main/scala/libretto/CoreLib.scala b/core/src/main/scala/libretto/CoreLib.scala
index 9ea08b4c..147dc9b3 100644
--- a/core/src/main/scala/libretto/CoreLib.scala
+++ b/core/src/main/scala/libretto/CoreLib.scala
@@ -5,6 +5,7 @@ import libretto.lambda.util.SourcePos
 import libretto.util.unapply.*
 import libretto.util.{Equal, ∀}
 import scala.annotation.tailrec
+import scala.annotation.nowarn
 
 object CoreLib {
   def apply(dsl: CoreDSL): CoreLib[dsl.type] =
@@ -1199,6 +1200,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
   def selectAgainstR[A](using A: SignalingJunction.Negative[A]): (A |&| A) -⚬ (A |*| Need) =
     |&|.swap > selectAgainstL > swap
 
+  @nowarn("msg=match may not be exhaustive")
   def racePreferred[A, B](using
     A: Signaling.Positive[A],
     B: Signaling.Positive[B],
@@ -1215,6 +1217,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
     }
   }
 
+  @nowarn("msg=match may not be exhaustive")
   def raceHandicap[A, B, C](f: (Ping |*| B) -⚬ C)(using
     A: Signaling.Positive[A],
     C: Signaling.Positive[C],
@@ -3533,6 +3536,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
     /** Merges the two lists as they unfold, i.e. as soon as the next element becomes available in one of the lists,
      *  it also becomes available as the next element of the result list.
      */
+    @nowarn("msg=match may not be exhaustive")
     def merge[T]: (LList[T] |*| LList[T]) -⚬ LList[T] = rec { self =>
       λ { case as |*| bs =>
         race(as |*| bs) switch {
@@ -3557,6 +3561,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
      *  their timely appearence in the input list is sufficient for them to come before
      *  the inserted element.
      */
+    @nowarn("msg=match may not be exhaustive")
     def insertBySignal[T](using Signaling.Positive[T]): (T |*| LList[T]) -⚬ LList[T] =
       rec { self =>
         λ { case a |*| as =>
@@ -3892,6 +3897,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
     def mapSequentially[A, B](f: A -⚬ B)(using Signaling.Positive[B]): Endless[A] -⚬ Endless[B] =
       mapSequence(f > notifyPosFst)
 
+    @nowarn("msg=match may not be exhaustive")
     def foldLeftSequentially[B, A](f: (B |*| A) -⚬ B)(using
       Signaling.Positive[B]
     ): (B |*| Endless[A]) -⚬ B =
@@ -3957,6 +3963,7 @@ class CoreLib[DSL <: CoreDSL](val dsl: DSL) { lib =>
       def go: ((A |*| Endless[A]) |*| Endless[A]) -⚬ Endless[A] = rec { self =>
         λ { case (a |*| as) |*| bs =>
           val po |*| pi = constant(lInvertPongPing)
+          @nowarn("msg=match may not be exhaustive")
           val res: $[One |&| (A |*| Endless[A])] =
             race[Ping, A](pi |*| a) switch {
               case Left(?(_) |*| a) =>
diff --git a/core/src/main/scala/libretto/InvertLib.scala b/core/src/main/scala/libretto/InvertLib.scala
index eb5cec73..b09182c4 100644
--- a/core/src/main/scala/libretto/InvertLib.scala
+++ b/core/src/main/scala/libretto/InvertLib.scala
@@ -1,6 +1,7 @@
 package libretto
 
 import libretto.lambda.util.SourcePos
+import scala.annotation.nowarn
 
 object InvertLib {
   def apply(
@@ -54,6 +55,7 @@ class InvertLib[
     ): $[(A |*| B) |+| (A |*| B)] =
       coreLib.race[A, B](a |*| b)
 
+    @nowarn("msg=match may not be exhaustive")
     def race[B](using SourcePos, LambdaContext)(b: ??[B])(using
       Signaling.Positive[A],
       Signaling.Negative[B],
diff --git a/core/src/main/scala/libretto/scaletto/ScalettoLib.scala b/core/src/main/scala/libretto/scaletto/ScalettoLib.scala
index 6a2d7243..7b686b6a 100644
--- a/core/src/main/scala/libretto/scaletto/ScalettoLib.scala
+++ b/core/src/main/scala/libretto/scaletto/ScalettoLib.scala
@@ -8,6 +8,7 @@ import scala.annotation.targetName
 import scala.concurrent.duration.*
 import scala.reflect.TypeTest
 import scala.util.Random
+import scala.annotation.nowarn
 
 object ScalettoLib {
   def apply(
@@ -117,6 +118,7 @@ class ScalettoLib[
   def delayValRandomMs[A](minMs: Int, maxMs: Int): Val[A] -⚬ Val[A] =
     delayVal(delayRandomMs(minMs, maxMs))
 
+  @nowarn("msg=match may not be exhaustive")
   def latestValue[A]: (Val[A] |*| LList[Val[A]]) -⚬ (Endless[Val[A]] |*| Done) = rec { self =>
     λ { case +(a) |*| as =>
       producing { case outAs |*| outDone =>
diff --git a/core/src/main/scala/libretto/scaletto/impl/futurebased/FutureExecutor.scala b/core/src/main/scala/libretto/scaletto/impl/futurebased/FutureExecutor.scala
index 48570f0d..1cc77248 100644
--- a/core/src/main/scala/libretto/scaletto/impl/futurebased/FutureExecutor.scala
+++ b/core/src/main/scala/libretto/scaletto/impl/futurebased/FutureExecutor.scala
@@ -8,6 +8,7 @@ import libretto.scaletto.ScalettoExecutor
 import libretto.scaletto.impl.FreeScaletto
 import libretto.util.Async
 import scala.concurrent.ExecutionContext
+import scala.annotation.nowarn
 
 object FutureExecutor {
   def apply(
@@ -29,6 +30,7 @@ object FutureExecutor {
     override def scheduler(s: Scheduler): ExecutionParam[Unit] =
       ExecutionParams.Free.wrap(SchedulerParam(s))
 
+    @nowarn("msg=type test")
     def extract[A](pa: ExecutionParam[A]): (Option[Scheduler], A) = {
       import ExecutionParams.Free.{One, Zip, Ext}
       pa match {
diff --git a/examples/src/main/scala/libretto/examples/interactionNets/unaryArithmetic/package.scala b/examples/src/main/scala/libretto/examples/interactionNets/unaryArithmetic/package.scala
index 0e436d9c..980474ce 100644
--- a/examples/src/main/scala/libretto/examples/interactionNets/unaryArithmetic/package.scala
+++ b/examples/src/main/scala/libretto/examples/interactionNets/unaryArithmetic/package.scala
@@ -27,6 +27,7 @@ object Wire {
     def dup   : (Wire |*| Wire) -⚬ Proper = injectL ∘ injectR
     def eraser: One             -⚬ Proper = injectR
 
+    @nowarn("msg=match may not be exhaustive")
     def switchWith[A, R](
       caseZero: A -⚬ R,
       caseSucc: (A |*| Wire) -⚬ R,
@@ -192,6 +193,7 @@ object Wire {
 }
 
 import Wire.Outlet
+import scala.annotation.nowarn
 
 enum Result {
   case Zero
diff --git a/examples/src/main/scala/libretto/examples/sunflowers/SunflowerProcessingFacility.scala b/examples/src/main/scala/libretto/examples/sunflowers/SunflowerProcessingFacility.scala
index 0055649e..d63d3956 100644
--- a/examples/src/main/scala/libretto/examples/sunflowers/SunflowerProcessingFacility.scala
+++ b/examples/src/main/scala/libretto/examples/sunflowers/SunflowerProcessingFacility.scala
@@ -3,8 +3,10 @@ package libretto.examples.sunflowers
 import libretto.scaletto.StarterKit.*
 import libretto.stream.scaletto.DefaultStreams.ValSource
 import libretto.stream.scaletto.DefaultStreams.ValSource.{Polled, fromChoice, notifyAction, poll}
+import scala.annotation.nowarn
 
 object SunflowerProcessingFacility {
+  @nowarn("msg=match may not be exhaustive")
   def blueprint: ValSource[Sunflower] -⚬ (ValSource[SeedsPack] |*| ValSource[OilBottle]) = rec { self =>
     λ { sunflowers =>
       // give names to the outputs
diff --git a/lambda/src/main/scala/libretto/lambda/Bin.scala b/lambda/src/main/scala/libretto/lambda/Bin.scala
index 4aa4c113..2194a58b 100644
--- a/lambda/src/main/scala/libretto/lambda/Bin.scala
+++ b/lambda/src/main/scala/libretto/lambda/Bin.scala
@@ -2,6 +2,7 @@ package libretto.lambda
 
 import libretto.lambda.util.{BiInjective, Exists, Injective, Masked, TypeEq, UniqueTypeArg}
 import libretto.lambda.util.TypeEq.Refl
+import scala.annotation.nowarn
 
 /**
  * Binary tree with leafs holding values of types `F[X]`, `F[Y]`, ...
@@ -92,6 +93,7 @@ sealed trait Bin[<*>[_, _], T[_], F[_], A] {
     ) extends Partitioned[G, H, ~⚬]
   }
 
+  @nowarn("msg=type test")
   def deduplicateLeafs[->[_, _]](
     dup: [x] => F[x] => T[x] -> (T[x] <*> T[x]),
   )(using
@@ -294,6 +296,7 @@ object Bin {
   case class Branch[<*>[_, _], T[_], F[_], A, B](l: Bin[<*>, T, F, A], r: Bin[<*>, T, F, B]) extends Bin[<*>, T, F, A <*> B]
   case class Leaf[<*>[_, _], T[_], F[_], A](value: F[A]) extends Bin[<*>, T, F, T[A]]
 
+  @nowarn("msg=match may not be exhaustive")
   def branchesOf[<*>[_, _], T[_], F[_], A, B](tree: Bin[<*>, T, F, A <*> B])(using
     leafIsNotBranch: [x, y, z] => (T[x] =:= (y <*> z)) => Nothing,
   )(using
@@ -311,6 +314,7 @@ object Bin {
         }
     )
 
+  @nowarn("msg=match may not be exhaustive")
   def valueOf[<*>[_, _], T[_], F[_], A](tree: Bin[<*>, T, F, T[A]])(using
     leafIsNotBranch: [x, y, z] => (T[x] =:= (y <*> z)) => Nothing,
   )(using
diff --git a/lambda/src/main/scala/libretto/lambda/Lambdas.scala b/lambda/src/main/scala/libretto/lambda/Lambdas.scala
index 936d9a39..1fc1eebc 100644
--- a/lambda/src/main/scala/libretto/lambda/Lambdas.scala
+++ b/lambda/src/main/scala/libretto/lambda/Lambdas.scala
@@ -4,6 +4,7 @@ import libretto.lambda.Lambdas.Error
 import libretto.lambda.Lambdas.Error.LinearityViolation
 import libretto.lambda.util.{Applicative, BiInjective, Exists, UniqueTypeArg}
 import scala.annotation.targetName
+import scala.annotation.nowarn
 
 trait Lambdas[-⚬[_, _], |*|[_, _], V] {
   final type Tupled[F[_], A] = libretto.lambda.Tupled[|*|, F, A]
@@ -130,6 +131,7 @@ trait Lambdas[-⚬[_, _], |*|[_, _], V] {
     Context,
   ): AbsRes[A, B]
 
+  @nowarn("msg=match may not be exhaustive")
   protected def switchImpl[<+>[_, _], A, B](
     cases: Sink[VFun, <+>, A, B],
     sum: [X, Y] => (X -⚬ B, Y -⚬ B) => (X <+> Y) -⚬ B,
diff --git a/lambda/src/main/scala/libretto/lambda/LambdasImpl.scala b/lambda/src/main/scala/libretto/lambda/LambdasImpl.scala
index ac4a9ff0..a8d8aab1 100644
--- a/lambda/src/main/scala/libretto/lambda/LambdasImpl.scala
+++ b/lambda/src/main/scala/libretto/lambda/LambdasImpl.scala
@@ -6,6 +6,7 @@ import libretto.lambda.Lambdas.Error.LinearityViolation
 import libretto.lambda.util.{Applicative, BiInjective, Exists, Injective, Masked, TypeEq, UniqueTypeArg}
 import libretto.lambda.util.TypeEq.Refl
 import scala.annotation.{tailrec, targetName}
+import scala.annotation.nowarn
 
 class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
   ssc: SymmetricSemigroupalCategory[-⚬, |*|],
@@ -631,6 +632,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         override def cap2_gcd_this[T, Y](that: CaptureSnd[T, Y])(using ev: (Var[A1] |*| Var[A2]) =:= Var[T]): Option[Tail[Var[T], Var[T |*| Y] |*| Var[A1 |*| A2]]] =
           varIsNotPair(ev.flip)
 
+        @nowarn("msg=match may not be exhaustive")
         override def asZip[P1, P2](using
           ev: (Var[A1] |*| Var[A2]) =:= (P1 |*| P2),
         ): Exists[[V1] =>> Exists[[V2] =>> (Zip[V1, V2], P1 =:= Var[V1], P2 =:= Var[V2], Var[A1 |*| A2] =:= Var[V1 |*| V2])]] =
@@ -702,6 +704,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
             case (None, Some(_)) =>
               bug(s"Variable ${that.resultVar} appeared as a result of two different projections")
 
+        @nowarn("msg=match may not be exhaustive")
         override def unzip_gcd_this[T1, T2](that: Unzip[T1, T2])(using
           ev: Var[A1 |*| A2] =:= Var[T1 |*| T2],
         ): Option[Tail[Var[T1 |*| T2], (Var[T1] |*| Var[T2]) |*| Var[A1]]] =
@@ -855,6 +858,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         override def unzip_gcd_this[T1, T2](that: Unzip[T1, T2])(using ev: Var[A] =:= Var[T1 |*| T2]): Option[Tail[Var[T1 |*| T2], (Var[T1] |*| Var[T2]) |*| Var[X |*| A]]] =
           UnhandledCase.raise(s"${this.getClass.getSimpleName}.unzip_gcd_this")
 
+        @nowarn("msg=match may not be exhaustive")
         override def cap1_gcd_this[T, Y](that: CaptureFst[T, Y])(using ev: Var[A] =:= Var[T]): Option[Tail[Var[T], Var[Y |*| T] |*| Var[X |*| A]]] =
           ev match { case Injective[Var](TypeEq(Refl())) =>
             (that.resultVar testEqual this.resultVar) map {
@@ -889,6 +893,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         override def cap1_gcd_this[T, Y](that: CaptureFst[T, Y])(using Var[A] =:= Var[T]): Option[Tail[Var[T], Var[Y |*| T] |*| Var[A |*| X]]] =
           None
 
+        @nowarn("msg=match may not be exhaustive")
         override def cap2_gcd_this[T, Y](that: CaptureSnd[T, Y])(using ev: Var[A] =:= Var[T]): Option[Tail[Var[T], Var[T |*| Y] |*| Var[A |*| X]]] =
           ev match { case Injective[Var](TypeEq(Refl())) =>
             (that.resultVar testEqual this.resultVar) map {
@@ -935,6 +940,8 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
           }
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       def gcd[C[_], D[_], X, Y, Z](
         f: Op.Affine[C[Var[X]], Y],
         g: Op.Affine[D[Var[X]], Z],
@@ -964,6 +971,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         }
       }
 
+      @nowarn("msg=match may not be exhaustive")
       private def gcdZips[A1, A2, B1, B2](
         z1: Zip[A1, A2],
         z2: Zip[B1, B2],
@@ -1070,6 +1078,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         case Op.Prj2(_, _)       => None
     }
 
+    @nowarn("msg=match may not be exhaustive")
     def pullBumpDupVar[A, F[_], V, C[_], B, D[_], Y](
       pre: Tail[A, F[Var[V]]],
       post: Tail[F[C[Var[V]]], B],
@@ -1211,6 +1220,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
   }
   object Unvar {
     case class SingleVar[V]() extends Unvar[Var[V], V] {
+      @nowarn("msg=match may not be exhaustive")
       override def uniqueOutType[C](that: Unvar[Var[V], C]): V =:= C =
         that.maskInput.visit([VV] => (that: Unvar[VV, C], ev: VV =:= Var[V]) => {
           that match {
@@ -1225,6 +1235,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
     }
 
     case class Par[A1, A2, X1, X2](u1: Unvar[A1, X1], u2: Unvar[A2, X2]) extends Unvar[A1 |*| A2, X1 |*| X2] {
+      @nowarn("msg=match may not be exhaustive")
       override def uniqueOutType[C](that: Unvar[A1 |*| A2, C]): (X1 |*| X2) =:= C =
         that.maskInput.visit([A] => (that: Unvar[A, C], ev: A =:= (A1 |*| A2)) => {
           that match {
@@ -1248,6 +1259,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
         override def pair[A1, A2, X1, X2](f1: Unvar[A1, X1], f2: Unvar[A2, X2]): Unvar[A1 |*| A2, X1 |*| X2] =
           Unvar.Par(f1, f2)
 
+        @nowarn("msg=match may not be exhaustive")
         override def unpair[A1, A2, X](f: Unvar[A1 |*| A2, X]): Unpaired[A1, A2, X] =
           f.maskInput.visit[Unpaired[A1, A2, X]]([A] => (u: Unvar[A, X], ev: A =:= (A1 |*| A2)) => {
             u match {
@@ -1266,6 +1278,7 @@ class LambdasImpl[-⚬[_, _], |*|[_, _], V](using
     [V, A, B] => (ev: Var[V] =:= (A |*| B)) => throw new AssertionError("Var[A] =:= (A |*| B)")
 
   extension[F[_], V, U](ev: F[Var[V]] =:= (Var[U] |*| Var[U])) {
+    @nowarn("msg=match may not be exhaustive")
     def deriveEquality(f: Focus[|*|, F]): V =:= U =
       f match {
         case f: Focus.Fst[pair, f1, q] =>
diff --git a/lambda/src/main/scala/libretto/lambda/Projection.scala b/lambda/src/main/scala/libretto/lambda/Projection.scala
index 8d9ac71d..fe6babc2 100644
--- a/lambda/src/main/scala/libretto/lambda/Projection.scala
+++ b/lambda/src/main/scala/libretto/lambda/Projection.scala
@@ -2,6 +2,7 @@ package libretto.lambda
 
 import libretto.lambda.util.{BiInjective, Exists, TypeEq}
 import libretto.lambda.util.TypeEq.Refl
+import scala.annotation.nowarn
 
 sealed trait Projection[|*|[_, _], P, Q] {
   def at[F[_]](f: Focus[|*|, F]): Projection[|*|, F[P], F[Q]]
@@ -73,6 +74,8 @@ object Projection {
         switchFromPair[P1, P2, R](caseDiscardFst, caseDiscardSnd, casePar)
     }
 
+    @nowarn("msg=match may not be exhaustive")
+    @nowarn("msg=type test")
     def switchFromPair[P1, P2, R](using ev: P =:= (P1 |*| P2))(
       caseDiscardFst: (p2: Projection[|*|, P2, Q]) => R,
       caseDiscardSnd: (p1: Projection[|*|, P1, Q]) => R,
diff --git a/lambda/src/main/scala/libretto/lambda/Shuffle.scala b/lambda/src/main/scala/libretto/lambda/Shuffle.scala
index 998c04d4..9724f398 100644
--- a/lambda/src/main/scala/libretto/lambda/Shuffle.scala
+++ b/lambda/src/main/scala/libretto/lambda/Shuffle.scala
@@ -5,6 +5,7 @@ import libretto.lambda.util.{BiInjective, Exists, TypeEq}
 import libretto.lambda.util.BiInjective.*
 import libretto.lambda.util.TypeEq.Refl
 import libretto.lambda.Projection.Proper
+import scala.annotation.nowarn
 
 class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
   sealed trait ~⚬[A, B] {
@@ -180,7 +181,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         }
 
       override def chaseFw[F[_], T](i: Focus[|*|, F])(using ev: (A1 |*| A2) =:= F[T]): ChaseFwRes[F, T, B1 |*| B2] = {
-        val res0: ChaseFwRes[F, T, X1 |*| X2] =
+        @nowarn("msg=match may not be exhaustive") val res0: ChaseFwRes[F, T, X1 |*| X2] =
           i match
             case Focus.Id() =>
               ChaseFwRes.Split(summon[T =:= F[T]] andThen ev.flip)
@@ -356,6 +357,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         override def after[F0[_]](f: [x] => Unit => F0[x] ~⚬ F[x]): ChaseFwRes[F0, X, B] =
           Transported[F0, X, G, B]([t] => (_: Unit) => f[t](()) > s[t](()), g, ev)
 
+        @nowarn("msg=match may not be exhaustive")
         override def thenSnd[B1, B2, C](f: B2 ~⚬ C)(using ev1: B =:= (B1 |*| B2)): ChaseFwRes[F, X, B1 |*| C] =
           g match {
             case Focus.Id() =>
@@ -428,6 +430,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
             [t] => (_: Unit) => par(fst, s[t](())),
           )
 
+        @nowarn("msg=match may not be exhaustive")
         override def afterAssocLR[A1, A2, A3](using ev1: (A2 |*| A3) =:= A): ChaseBwRes[(A1 |*| A2) |*| A3, [x] =>> A1 |*| G[x], X] =
           f match {
             case Focus.Id() =>
@@ -450,6 +453,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               }
           }
 
+        @nowarn("msg=match may not be exhaustive")
         override def afterAssocRL[A1, A2, A3](using ev1: (A1 |*| A2) =:= A): ChaseBwRes[A1 |*| (A2 |*| A3), [x] =>> G[x] |*| A3, X] =
           f match {
             case Focus.Id() =>
@@ -472,6 +476,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               }
           }
 
+        @nowarn("msg=match may not be exhaustive")
         override def afterXI[A1, A2, A3](using ev1: (A1 |*| A3) =:= A): ChaseBwRes[A1 |*| (A2 |*| A3), [x] =>> A2 |*| G[x], X] =
           f match {
             case Focus.Id() =>
@@ -494,6 +499,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               }
             }
 
+        @nowarn("msg=match may not be exhaustive")
         override def afterIX[A1, A2, A3](using ev1: (A1 |*| A3) =:= A): ChaseBwRes[(A1 |*| A2) |*| A3, [x] =>> G[x] |*| A2, X] =
           f match {
             case Focus.Id() =>
@@ -516,6 +522,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               }
           }
 
+        @nowarn("msg=match may not be exhaustive")
         override def afterIXI1[A1, A2, A3, A4](using ev1: (A1 |*| A3) =:= A): ChaseBwRes[(A1 |*| A2) |*| (A3 |*| A4), [x] =>> G[x] |*| (A2 |*| A4), X] =
           f match {
             case Focus.Id() =>
@@ -672,6 +679,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
       }}}}
     }
 
+    @nowarn("msg=match may not be exhaustive")
     def chaseFw[F[_], T](i: Focus[|*|, F])(using ev: (X1 |*| X2) =:= F[T]): ChaseFwRes[F, T, Y1 |*| Y2] =
       i match {
         case Focus.Id() =>
@@ -706,6 +714,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
           }
       }
 
+    @nowarn("msg=match may not be exhaustive")
     def chaseBw[G[_], T](i: Focus[|*|, G])(using ev: (Y1 |*| Y2) =:= G[T]): ChaseBwRes[X1 |*| X2, G, T] =
       i match {
         case Focus.Id() =>
@@ -762,6 +771,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
     def chaseBwFst[G[_], T](i: Focus[|*|, G])(using B1 =:= G[T]): ChaseBwRes[A1 |*| A2, [t] =>> G[t] |*| B2, T]
     def chaseBwSnd[G[_], T](i: Focus[|*|, G])(using B2 =:= G[T]): ChaseBwRes[A1 |*| A2, [t] =>> B1 |*| G[t], T]
 
+    @nowarn("msg=match may not be exhaustive")
     final def translate[<*>[_, _], F[_, _], S](
       fa: F[A1 |*| A2, S],
     )(
@@ -1051,6 +1061,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
       }
     }
 
+    @nowarn("msg=match may not be exhaustive")
     final override def chaseFw[F[_], T](i: Focus[|*|, F])(using ev: F[T] =:= (A1 |*| A2)): ChaseFwRes[F, T, B1 |*| B2] =
       i match {
         case Focus.Id() =>
@@ -1065,6 +1076,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               chaseFwSnd[f2, T](snd.i)
       }
 
+    @nowarn("msg=match may not be exhaustive")
     final override def chaseBw[G[_], T](i: Focus[|*|, G])(using ev: (B1 |*| B2) =:= G[T]): ChaseBwRes[A1 |*| A2, G, T] =
       i match {
         case Focus.Id() =>
@@ -1311,6 +1323,8 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         F.zip(a1, g(F.zip(a2, a3)))
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       override def translateLR[<*>[_,_], F[_,_], S12, S3](
         fa12: F[A1 |*| A2, S12],
         fa3 : F[A3, S3],
@@ -1325,6 +1339,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         }}
       }
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateRL[<*>[_, _], F[_, _], T1, T2](
         fa1: F[A1, T1],
         fb23: F[B2 |*| B3, T2],
@@ -1340,6 +1355,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
                 Exists(Exists((m.pair(fa1, fa2), fa3, tgt.Transfer.AssocLR(h))))
       }
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwFst[F[_], T](i: Focus[|*|, F])(using
         ev: F[T] =:= (A1 |*| A2),
       ): ChaseFwRes[[t] =>> F[t] |*| A3, T, A1 |*| (B2 |*| B3)] =
@@ -1400,6 +1416,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               Xfer(assocLR[A11, A12, A2] > snd(f1), f2, AssocLR(g))
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenAssocRL[B21, B22, C1, C2](
         that: AssocRL[A1, B21, B22, C1, C2],
       )(using
@@ -1423,6 +1440,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
           case Decomposition(f1, f2, h) => Xfer(fst(Id0(ev)) > ix > fst(f1), f2, IX(h))
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenXI[B21, B22, C2, C3](
         that: XI[A1, B21, B22, C2, C3],
       )(using
@@ -1573,6 +1591,8 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         F.zip(g(F.zip(a1, a2)), a3)
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       override def translateLR[<*>[_, _], F[_, _], S1, S23](
         fa1: F[A1, S1],
         fa23: F[A2 |*| A3, S23],
@@ -1586,6 +1606,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         Exists(Exists((tgt.Transfer.AssocRL[S1, v.X1, v.X2, e1.T, e2.T](g1), m.pair(fb1, fb2), fa3)))
         }}
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateRL[<*>[_, _], F[_, _], T1, T2](
         fb12: F[B1 |*| B2, T1],
         fa3: F[A3, T2],
@@ -1607,6 +1628,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
             .after([t] => (_: Unit) => assocRL[F[t], A2, A3])
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwSnd[F[_], T](i: Focus[|*|, F])(using ev: F[T] =:= (A2 |*| A3)): ChaseFwRes[[t] =>> A1 |*| F[t], T, (B1 |*| B2) |*| A3] =
         i match {
           case Focus.Id() =>
@@ -1649,6 +1671,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
           case Decomposition(f1, f2, h) => Xfer(f1, fst(f2) > swap, XI(h))
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenAssocLR[D1, D2, C2, C3](
         that: AssocLR[D1, D2, A3, C2, C3],
       )(using
@@ -1837,6 +1860,8 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         F.zip(g(F.zip(a1, a3)), a2)
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       override def translateLR[<*>[_, _], F[_, _], S12, S3](
         fa12: F[A1 |*| A2, S12],
         fa3: F[A3, S3],
@@ -1851,6 +1876,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               case e1 @ Exists.Some(e2 @ Exists.Some((g1, fb1, fb2))) =>
                 Exists(Exists((tgt.Transfer.IX[v.X1, v.X2, S3, e1.T, e2.T](g1), m.pair(fb1, fb2), fa2)))
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateRL[<*>[_, _], F[_, _], T1, T2](
         fb12: F[B1 |*| B2, T1],
         fa2: F[A2, T2],
@@ -1865,6 +1891,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               case Exists.Some(Exists.Some((fa1, fa3, g1))) =>
                 Exists(Exists((m.pair(fa1, fa2), fa3, tgt.Transfer.IX(g1))))
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwFst[F[_], T](i: Focus[|*|, F])(using ev: F[T] =:= (A1 |*| A2)): ChaseFwRes[[t] =>> F[t] |*| A3, T, (B1 |*| B2) |*| A2] =
         ev match { case TypeEq(Refl()) =>
           i match
@@ -2107,6 +2134,8 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         F.zip(a2, g(F.zip(a1, a3)))
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       override def translateLR[<*>[_, _], F[_, _], S1, S23](
         fa1: F[A1, S1],
         fa23: F[A2 |*| A3, S23],
@@ -2121,6 +2150,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               case e1 @ Exists.Some(e2 @ Exists.Some((g1, fb2, fb3))) =>
                 Exists(Exists((tgt.Transfer.XI[S1, v.X1, v.X2, e1.T, e2.T](g1), fa2, m.pair(fb2, fb3))))
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateRL[<*>[_, _], F[_, _], T1, T2](
         fb1: F[A2, T1],
         fb23: F[B2 |*| B3, T2],
@@ -2145,12 +2175,13 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
           ).thenSnd[A2, A1 |*| A3, B2 |*| B3](g.asShuffle)
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwSnd[F[_], T](i: Focus[|*|, F])(using ev: F[T] =:= (A2 |*| A3)): ChaseFwRes[[t] =>> A1 |*| F[t], T, A2 |*| (B2 |*| B3)] =
         i match {
           case Focus.Id() =>
             ChaseFwRes.Split(ev)
           case i: Focus.Fst[pair, f1, z] =>
-            (summon[(f1[T] |*| z) =:= F[T]] andThen ev)                                               match { case BiInjective[|*|](TypeEq(Refl()), TypeEq(Refl())) =>
+            (summon[(f1[T] |*| z) =:= F[T]] andThen ev) match { case BiInjective[|*|](TypeEq(Refl()), TypeEq(Refl())) =>
               type G[t] = A1 |*| (f1[t] |*| A3)
               type H[t] = f1[t] |*| (B2 |*| B3)
               ChaseFwRes.Transported[G, T, H, A2 |*| (B2 |*| B3)](
@@ -2160,7 +2191,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               )
             }
           case i: Focus.Snd[pair, f2, z] =>
-            (summon[(z |*| f2[T]) =:= F[T]] andThen ev)                                               match { case BiInjective[|*|](TypeEq(Refl()), TypeEq(Refl())) =>
+            (summon[(z |*| f2[T]) =:= F[T]] andThen ev) match { case BiInjective[|*|](TypeEq(Refl()), TypeEq(Refl())) =>
               g.chaseFw[[x] =>> A1 |*| f2[x], T](i.i.inSnd[A1])
                 .inSnd[A2]
                 .after([x] => (_: Unit) => xi[A1, A2, f2[x]])
@@ -2198,6 +2229,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               Xfer(f1, assocLR[A21, A22, A3] > snd(f2), XI(g))
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenAssocRL[B2_, B3_, C1, C2](
         that: AssocRL[A2, B2_, B3_, C1, C2],
       )(using
@@ -2225,6 +2257,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
               Xfer(f1, ix[A21, A22, A3] > fst(f2), AssocRL(h))
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenXI[B2_, B3_, C2, C3](
         that: XI[A2, B2_, B3_, C2, C3],
       )(using
@@ -2239,6 +2272,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
                 t.xi_this_xi(that)
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenIXI[B11, B12, B21, B22, C1, C2, C3, C4](
         that: IXI[B11, B12, B21, B22, C1, C2, C3, C4]
       )(using
@@ -2393,6 +2427,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         F.zip(g1(F.zip(a1, a3)), g2(F.zip(a2, a4)))
       }
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateLR[<*>[_, _], F[_, _], S1, S2](
         fa12: F[A1 |*| A2, S1],
         fa34: F[A3 |*| A4, S2],
@@ -2412,6 +2447,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
         )))
         }}}}
 
+      @nowarn("msg=match may not be exhaustive")
       override def translateRL[<*>[_, _], F[_, _], T1, T2](
         fb12: F[B1 |*| B2, T1],
         fb34: F[B3 |*| B4, T2],
@@ -2430,6 +2466,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
                       case Exists.Some(Exists.Some((fa2, fa4, h2))) =>
                         Exists(Exists((m.pair(fa1, fa2), m.pair(fa3, fa4), tgt.Transfer.IXI(h1, h2))))
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwFst[F[_], T](i: Focus[|*|, F])(using
         ev: F[T] =:= (A1 |*| A2),
       ): ChaseFwRes[[t] =>> F[t] |*| (A3 |*| A4), T, B1 |*| B2 |*| (B3 |*| B4)] =
@@ -2450,6 +2487,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
                   .after([t] => (_: Unit) => ixi[A1, f2[t], A3, A4])
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def chaseFwSnd[F[_], T](i: Focus[|*|, F])(using
         ev: F[T] =:= (A3 |*| A4),
       ): ChaseFwRes[[t] =>> A1 |*| A2 |*| F[t], T, B1 |*| B2 |*| (B3 |*| B4)] =
@@ -2517,6 +2555,7 @@ class Shuffle[|*|[_, _]](using inj: BiInjective[|*|]) {
             t.ixi_sndThis_assocRL(g1, that)
         }
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenIX[B1_, B2_, C1, C2](
         that: IX[B1_, B2_, B3 |*| B4, C1, C2],
       )(using
diff --git a/lambda/src/main/scala/libretto/lambda/Shuffled.scala b/lambda/src/main/scala/libretto/lambda/Shuffled.scala
index 1ab328bf..ef41c517 100644
--- a/lambda/src/main/scala/libretto/lambda/Shuffled.scala
+++ b/lambda/src/main/scala/libretto/lambda/Shuffled.scala
@@ -4,6 +4,7 @@ import libretto.lambda.{Projection => P}
 import libretto.lambda.util.{Applicative, BiInjective, Exists, TypeEq}
 import libretto.lambda.util.TypeEq.Refl
 import libretto.lambda.Projection.Proper
+import scala.annotation.nowarn
 
 object Shuffled {
   type With[->[_, _], |*|[_, _], S <: Shuffle[|*|]] =
@@ -443,6 +444,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
       def chaseFwFst[F[_], X](i: Focus[|*|, F])(using ev: A1 =:= F[X]): ChaseFwRes.Blocked[[x] =>> F[x] |*| A2, X, B]
       def chaseFwSnd[F[_], X](i: Focus[|*|, F])(using ev: A2 =:= F[X]): ChaseFwRes.Blocked[[x] =>> A1 |*| F[x], X, B]
 
+      @nowarn("msg=match may not be exhaustive")
       final override def chaseFw[F[_], X](i: Focus[|*|, F])(using ev: (A1 |*| A2) =:= F[X]): ChaseFwRes.Blocked[F, X, B] =
         ev match { case TypeEq(Refl()) =>
           i match {
@@ -464,6 +466,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
       def chaseBwFst[G[_], X](i: Focus[|*|, G])(using B1 =:= G[X]): ChaseBwRes.Blocked[A, [x] =>> G[x] |*| B2, X]
       def chaseBwSnd[G[_], X](i: Focus[|*|, G])(using B2 =:= G[X]): ChaseBwRes.Blocked[A, [x] =>> B1 |*| G[x], X]
 
+      @nowarn("msg=match may not be exhaustive")
       final override def chaseBw[G[_], X](i: Focus[|*|, G])(using ev: (B1 |*| B2) =:= G[X]): ChaseBwRes.Blocked[A, G, X] =
         i match
           case Focus.Id() =>
@@ -775,6 +778,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
         (tgt.Plated.SemiCons(semiHead1, s, t, tail1), b)
       }
 
+      @nowarn("msg=match may not be exhaustive")
       override def translate[->>[_, _], <*>[_, _], F[_, _], S](
         fa: F[A1 |*| A2, S],
         om: ObjectMap[|*|, <*>, F],
@@ -874,6 +878,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
         (tgt.Plated.SemiSnoc(init1, t.rebase(tgt), s, sl1), F.zip(b1, b2))
       }
 
+      @nowarn("msg=match may not be exhaustive")
       override def translate[->>[_, _], <*>[_, _], F[_, _], S](
         fa: F[A, S],
         om: ObjectMap[|*|, <*>, F],
@@ -1003,6 +1008,8 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
         )
       }
 
+      @nowarn("msg=match may not be exhaustive")
+      @nowarn("msg=type test")
       override def translate[->>[_, _], <*>[_, _], F[_, _], S](
         fa: F[A1 |*| A2, S],
         om: ObjectMap[|*|, <*>, F],
@@ -1054,6 +1061,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
     def project[C](p: Projection[|*|, B1 |*| B2, C]): ProjectRes[A1 |*| A2, C] =
       ProjectRes(asShuffle.project(p))
 
+    @nowarn("msg=match may not be exhaustive")
     def translate[->>[_, _], <*>[_, _], F[_, _], S1, S2](
       fa1: F[A1, S1],
       fa2: F[A2, S2],
@@ -1320,6 +1328,7 @@ sealed abstract class Shuffled[->[_, _], |*|[_, _]](using BiInjective[|*|]) {
       override def andThen[C](that: Shuffled[B, C]): ChaseFwRes[F, X, C] =
         that.chaseFw[G, X](g)(using ev.flip).after(s)
 
+      @nowarn("msg=match may not be exhaustive")
       override def thenSnd[B1, B2, C2](using ev1: B =:= (B1 |*| B2))(that: Shuffled[B2, C2]): ChaseFwRes[F, X, B1 |*| C2] =
         g match {
           case g: Focus.Fst[pair, g1, b2] =>
diff --git a/lambda/src/test/scala/libretto/lambda/Fun.scala b/lambda/src/test/scala/libretto/lambda/Fun.scala
index 1f7e251f..daea7592 100644
--- a/lambda/src/test/scala/libretto/lambda/Fun.scala
+++ b/lambda/src/test/scala/libretto/lambda/Fun.scala
@@ -3,6 +3,7 @@ package libretto.lambda
 import libretto.lambda.Lambdas.Error.LinearityViolation.{OverUnder, Overused, Underused}
 import libretto.lambda.util.{BiInjective, SourcePos, TypeEq}
 import libretto.lambda.util.TypeEq.Refl
+import scala.annotation.nowarn
 
 sealed trait Fun[A, B] {
 
@@ -222,6 +223,7 @@ object Fun {
     case Pair[A, B](_1: Values[A], _2: Values[B]) extends Values[A ** B]
   }
 
+  @nowarn("msg=match may not be exhaustive")
   private def evaluate[A, B](f: Fun[A, B])(a: Values[A]): Values[B] = {
     import Values.{Pair, SingleVal}
 
diff --git a/stream/src/main/scala/libretto/stream/CoreStreams.scala b/stream/src/main/scala/libretto/stream/CoreStreams.scala
index 0187af41..a4ffa57e 100644
--- a/stream/src/main/scala/libretto/stream/CoreStreams.scala
+++ b/stream/src/main/scala/libretto/stream/CoreStreams.scala
@@ -2,6 +2,7 @@ package libretto.stream
 
 import libretto.{CoreDSL, CoreLib}
 import libretto.lambda.util.Exists
+import scala.annotation.nowarn
 
 object CoreStreams {
   def apply(
@@ -568,6 +569,7 @@ class CoreStreams[DSL <: CoreDSL, Lib <: CoreLib[DSL]](
       val sndClosed: Source[A |+| B] -⚬ (Polled[A] |*| Done) =
         close[A |+| B].introFst(done > Polled.empty[A])
 
+      @nowarn("msg=match may not be exhaustive")
       val bothPolled: Source[A |+| B] -⚬ (Polled[A] |*| Polled[B]) =
         λ { src =>
           poll(src) switch {
@@ -635,6 +637,7 @@ class CoreStreams[DSL <: CoreDSL, Lib <: CoreLib[DSL]](
           from(onClose, onPoll)
         }
 
+        @nowarn("msg=match may not be exhaustive")
         def go1: (Ping |*| (Polled[A] |*| Source[A])) -⚬ Source[A] =
           λ { case downstreamActing |*| (as |*| bs) =>
             (as :>> notifyEither) match {
@@ -767,6 +770,7 @@ class CoreStreams[DSL <: CoreDSL, Lib <: CoreLib[DSL]](
      *  If the input source runs out of elements before the input list does,
      *  the remaining elements of the input list are returned.
      */
+    @nowarn("msg=match may not be exhaustive")
     def takeForeach[X, A]: (LList[X] |*| Source[A]) -⚬ (LList[X |*| A] |*| LList[X] |*| Done) =
       rec { takeForeach =>
         λ { case (xs |*| as) =>
diff --git a/stream/src/main/scala/libretto/stream/scaletto/ScalettoStreams.scala b/stream/src/main/scala/libretto/stream/scaletto/ScalettoStreams.scala
index 69261f7f..fca577b2 100644
--- a/stream/src/main/scala/libretto/stream/scaletto/ScalettoStreams.scala
+++ b/stream/src/main/scala/libretto/stream/scaletto/ScalettoStreams.scala
@@ -6,6 +6,7 @@ import libretto.scaletto.{Scaletto, ScalettoLib}
 import libretto.stream.InvertStreams
 import scala.annotation.{tailrec, targetName}
 import scala.concurrent.duration.FiniteDuration
+import scala.annotation.nowarn
 
 object ScalettoStreams {
   type Of[
@@ -381,6 +382,7 @@ abstract class ScalettoStreams {
     def prefetch[A](n: Int): ValSource[A] -⚬ ValSource[A] =
       Source.prefetch[Val[A]](n)(neglect, Exists(inversionDuality[LList[Done]]))
 
+    @nowarn("msg=match may not be exhaustive")
     def dropUntilFirstDemand[A]: ValSource[A] -⚬ ValSource[A] = rec { self =>
       poll > λ { as =>
         producing { out =>
@@ -576,6 +578,7 @@ abstract class ScalettoStreams {
       def delayBy[A]: (Done |*| Polled[A]) -⚬ Polled[A] =
         Source.Polled.delayBy
 
+      @nowarn("msg=match may not be exhaustive")
       def dup[A](
         dupSource: ValSource[A] -⚬ (ValSource[A] |*| ValSource[A]),
       ): Polled[A] -⚬ (Polled[A] |*| Polled[A]) =
diff --git a/testing/src/main/scala/libretto/testing/scaletto/ScalettoTestExecutor.scala b/testing/src/main/scala/libretto/testing/scaletto/ScalettoTestExecutor.scala
index f17ac32c..79a30b12 100644
--- a/testing/src/main/scala/libretto/testing/scaletto/ScalettoTestExecutor.scala
+++ b/testing/src/main/scala/libretto/testing/scaletto/ScalettoTestExecutor.scala
@@ -7,6 +7,7 @@ import libretto.scaletto.{Scaletto, ScalettoBridge, ScalettoExecutor, StarterKit
 import libretto.testing.{ManualClock, ManualClockParams, TestExecutor, TestResult}
 import libretto.util.Async
 import scala.concurrent.duration.FiniteDuration
+import scala.annotation.nowarn
 
 object ScalettoTestExecutor {
   import ExecutionParam.Instantiation
@@ -85,6 +86,7 @@ object ScalettoTestExecutor {
         ExecutionParams.Free.wrap(ManualClockParam)
     }
 
+    @nowarn("msg=type test")
     def instantiate[A, P[_]](p: ExecutionParam[A])(using
       ep: ExecutionParams.WithScheduler[P],
     ): Instantiation[A, P] = {