clean up genprod, get rid of warning (scala#5361)

No more "Selecting value MAX_ARITY from object genprod, 
which extends scala.DelayedInit, is likely to yield an 
uninitialized value" at start of every build.

Author: SethTisue

src/build/genprod.scala

@@ -1,24 +1,22 @@
 /*                     __                                               *\
 **     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2002-2013, LAMP/EPFL             **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2016, LAMP/EPFL             **
 **  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
 ** /____/\___/_/ |_/____/_/ | |                                         **
 **                          |/                                          **
 \*                                                                      */
 
-import scala.language.postfixOps
-
 /** This program generates the ProductN, TupleN, FunctionN,
- *  and AbstractFunctionN, where 0 <= N <= MAX_ARITY.
+ *  and AbstractFunctionN, where 0 <= N <= MaxArity.
  *
  *    Usage: scala genprod <directory>
  *      where the argument is the desired output directory
  *
  *  @author  Burak Emir, Stephane Micheloud, Geoffrey Washburn, Paul Phillips
  */
 object genprod extends App {
-  val MAX_ARITY = 22
-  def arities = (1 to MAX_ARITY).toList
+  final val MaxArity = 22
+  def arities = (1 to MaxArity).toList
 
   class Group(val name: String) {
     def className(i: Int) = name + i
@@ -220,7 +218,7 @@ class Function(val i: Int) extends Group("Function") with Arity {
 """  /** Creates a curried version of this function.
    *
    *  @return   a function `f` such that `f%s == apply%s`
-   */""".format(xdefs map ("(" + _ + ")") mkString, commaXs)
+   */""".format(xdefs.map("(" + _ + ")").mkString, commaXs)
   }
 
   def tupleMethod = {
@@ -299,7 +297,7 @@ class Tuple(val i: Int) extends Group("Tuple") with Arity {
   // prettifies it a little if it's overlong
   def mkToString() = {
   def str(xs: List[String]) = xs.mkString(""" + "," + """)
-    if (i <= MAX_ARITY / 2) str(mdefs)
+    if (i <= MaxArity / 2) str(mdefs)
     else {
       val s1 = str(mdefs take (i / 2))
       val s2 = str(mdefs drop (i / 2))
@@ -363,7 +361,7 @@ class Product(val i: Int) extends Group("Product") with Arity {
   def cases = {
     val xs = for ((x, i) <- mdefs.zipWithIndex) yield "case %d => %s".format(i, x)
     val default = "case _ => throw new IndexOutOfBoundsException(n.toString())"
-    "\n" + ((xs ::: List(default)) map ("    " + _ + "\n") mkString)
+    "\n" + ((xs ::: List(default)).map("    " + _ + "\n").mkString)
   }
   def proj = {
     (mdefs,targs).zipped.map( (_,_) ).zipWithIndex.map { case ((method,typeName),index) =>
@@ -372,7 +370,7 @@ class Product(val i: Int) extends Group("Product") with Arity {
          |   */
          |  def %s: %s
          |""".stripMargin.format(index + 1, index + 1, method, typeName)
-    } mkString
+    }.mkString
   }
 
   def apply() = {