Add an option to emit explicit types for vals in ScalaCodegen

Author: Alexey Romanov

src/internal/Config.scala

@@ -5,6 +5,8 @@ trait Config {
   val verbosity = System.getProperty("lms.verbosity","0").toInt
   val sourceinfo = System.getProperty("lms.sourceinfo","0").toInt
   val addControlDeps = System.getProperty("lms.controldeps","true").toBoolean
+
+  val scalaExplicitTypes = System.getProperty("lms.scala.explicitTypes","false").toBoolean
 
   // memory management type for C++ target (refcnt or gc)
   val cppMemMgr = System.getProperty("lms.cpp.memmgr","malloc")

src/internal/ScalaCodegen.scala

@@ -95,7 +95,8 @@ trait ScalaCodegen extends GenericCodegen with Config {
       val context = sym.pos(0)
       "      // " + relativePath(context.fileName) + ":" + context.line
     }
-    stream.println("val " + quote(sym) + " = " + rhs + extra)
+    val typeSignature = if (scalaExplicitTypes) ": " + remap(sym.tp) else ""
+    stream.println("val " + quote(sym) + typeSignature + " = " + rhs + extra)
   }
 
   def emitVarDef(sym: Sym[Variable[Any]], rhs: String): Unit = {