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

@@ -99,13 +99,16 @@ trait ScalaCodegen extends GenericCodegen with Config {
   }
 
   def emitValDef(sym: Sym[Any], rhs: String): Unit = {
-    stream.println("val " + quote(sym) + " = " + rhs + valDefExtra(sym))
+    if (scalaExplicitTypes)
+      emitTypedValDef(sym, rhs)
+    else
+      stream.println(src"val $sym = $rhs" + valDefExtra(sym))
   }
 
   def emitTypedValDef(sym: Sym[Any], rhs: String): Unit = {
     stream.println(src"val $sym: ${sym.tp} = $rhs" + valDefExtra(sym))
   }
-  
+
   def emitVarDef(sym: Sym[Variable[Any]], rhs: String): Unit = {
     stream.println("var " + quote(sym) + ": " + remap(sym.tp) + " = " + rhs)
   }