Fix #323

Kotlin reflect doesn't support synthetic classes, but we are OK with that ATM. So, we simply return false for the classes Kotlin reflect doesn't support. If you want to implement some renderer with a more complex logic, you can proceed with a Java reflection.

Author: ileasile

jupyter-lib/api/src/main/kotlin/org/jetbrains/kotlinx/jupyter/api/renderersHandling.kt

@@ -135,7 +135,11 @@ class SubtypeRendererTypeHandler(private val superType: KClass<*>, override val
     }
 
     override fun acceptsType(type: KClass<*>): Boolean {
-        return type.isSubclassOf(superType)
+        return try {
+            type.isSubclassOf(superType)
+        } catch (e: UnsupportedOperationException) {
+            false
+        }
     }
 
     override fun replaceVariables(mapping: Map<String, String>): SubtypeRendererTypeHandler {

src/test/kotlin/org/jetbrains/kotlinx/jupyter/test/repl/ReplTests.kt

@@ -443,6 +443,18 @@ class ReplTests : AbstractSingleReplTest() {
 
         assertEquals("org.RDKit.RWMol", res!!::class.qualifiedName)
     }
+
+    @Test
+    fun testLambdaRendering() {
+        val res = eval(
+            """
+            val foo: (Int) -> Int = {it + 1}
+            foo
+            """.trimIndent()
+        ).resultValue!!
+        @Suppress("UNCHECKED_CAST")
+        assertEquals(2, (res as (Int) -> Int)(1))
+    }
 }
 
 class ReplVarsTest : AbstractSingleReplTest() {