Scala 3.0.1, with the simplification of given syntax.

Author: Dean Wampler

build.sbt

@@ -1,4 +1,4 @@
-val scala3 = "3.0.0"
+val scala3 = "3.0.1"
 lazy val root = project
   .in(file("."))
   .settings(

src/main/scala/progscala3/contexts/json/JSONBuilder.scala

@@ -102,14 +102,16 @@ object JSONBuilder:
    * are _witnesses_, constraining the allowed types of JSON values. Note that
    * there is nothing to implement in the trait, but we have to use the `with {}`
    * clauses to make these definitions concrete.
+   * NOTE: Scala 3.0.0 requires "given ValidJSONValue[Int] with {}", while 3.0.1
+   * removed the need for "with {}", but you have to add the "()".
    */
   sealed trait ValidJSONValue[T <: Matchable]
-  given ValidJSONValue[Int] with {}
-  given ValidJSONValue[Double] with {}
-  given ValidJSONValue[String] with {}
-  given ValidJSONValue[Boolean] with {}
-  given ValidJSONValue[JSONObject] with {}
-  given ValidJSONValue[JSONArray] with {}
+  given ValidJSONValue[Int]()
+  given ValidJSONValue[Double]()
+  given ValidJSONValue[String]()
+  given ValidJSONValue[Boolean]()
+  given ValidJSONValue[JSONObject]()
+  given ValidJSONValue[JSONArray]()
 
 
   /**

src/script/scala/progscala3/contexts/GivenImports.scala

@@ -23,8 +23,9 @@ trait Marker[T]
 object O2:
   class C1
   given C1 = C1()
-  given Marker[Int] with {}                 // <1>
-  given Marker[List[?]] with {}             // <2>
+  // In Scala 3.0.0, the following has to be written: given Marker[Int] with {}
+  given Marker[Int]()                 // <1>
+  given Marker[List[?]]()             // <2>
 
 import O2.{given Marker[?]}     // Import all given Markers
 import O2.{given Marker[Int]}   // Import just the Marker[Int]

src/script/scala/progscala3/contexts/UsingTypeErasureWorkaround.scala

@@ -3,8 +3,10 @@
 
 object O2:
   trait Marker[T]                                               // <1>
-  given IntMarker: Marker[Int] with {}
-  given StringMarker: Marker[String] with {}
+  // In Scala 3.0.0, the following has to be written:
+  // given IntMarker: Marker[Int] with {}
+  given IntMarker: Marker[Int]()
+  given StringMarker: Marker[String]()
 
   def m(is: Seq[Int])(using IntMarker.type): Int = is.sum       // <2>
   def m(ss: Seq[String])(using StringMarker.type): Int = ss.length

src/script/scala/progscala3/meta/compiletime/SummonAll.scala

@@ -2,8 +2,9 @@
 import scala.compiletime.summonAll
 
 trait C; trait D; trait E
-given c: C with {}
-given d: D with {}
+// In Scala 3.0.0, the following has to be written: given c: C with {}
+given c: C()
+given d: D()
 
 summonAll[C *: D *: EmptyTuple]
 summonAll[C *: D *: E *: EmptyTuple]                            // <1>

src/script/scala/progscala3/meta/compiletime/SummonFrom.scala

@@ -14,16 +14,17 @@ inline def trySummonFrom(label: String, expected: Int): Unit =  // <1>
 def tryNone = trySummonFrom("tryNone:", 0)                      // <2>
 
 def tryA =                                                      // <3>
-  given A with {}
+  // In Scala 3.0.0, the following has to be written: given A with {}
+  given A()
   trySummonFrom("tryA:", 1)
 
 def tryB =
-  given B with {}
+  given B()
   trySummonFrom("tryB:", 2)
 
 def tryAB =
-  given A with {}
-  given B with {}
+  given A()
+  given B()
   trySummonFrom("tryAB:", 1)
 
 tryNone; tryA; tryB; tryAB