Updated the way Leon renders strings

library/lang/StrOps.scala

@@ -18,22 +18,19 @@ object StrOps {
   def substring(a: String, start: BigInt, end: BigInt): String = {
     if(start > end || start >= length(a) || end <= 0) "" else a.substring(start.toInt, end.toInt)
   }
-  @ignore
+  @library
   def bigIntToString(a: BigInt): String = {
     a.toString
   }
-  @ignore
+  @library
   def intToString(a: Int): String = {
     a.toString
   }
-  @ignore
-  def doubleToString(a: Double): String = {
-    a.toString
-  }
+  @library
   def booleanToString(a: Boolean): String = {
     if(a) "true" else "false"
   }
-  @ignore
+  @library
   def charToString(a: Char): String = {
     a.toString
   }

src/main/scala/leon/purescala/PrettyPrinter.scala

@@ -167,11 +167,11 @@ class PrettyPrinter(opts: PrinterOptions,
       case Equals(l,r)          => optP { p"$l == $r" }
       
       
-      case Int32ToString(expr)    => p"StrOps.intToString($expr)"
-      case BooleanToString(expr)  => p"StrOps.booleanToString($expr)"
-      case IntegerToString(expr)  => p"StrOps.bigIntToString($expr)"
-      case CharToString(expr)     => p"StrOps.charToString($expr)"
-      case RealToString(expr)     => p"StrOps.realToString($expr)"
+      case Int32ToString(expr)    => p"$expr.toString"
+      case BooleanToString(expr)  => p"$expr.toString"
+      case IntegerToString(expr)  => p"$expr.toString"
+      case CharToString(expr)     => p"$expr.toString"
+      case RealToString(expr)     => p"$expr.toString"
       case StringConcat(lhs, rhs) => optP { p"$lhs + $rhs" }
     
       case SubString(expr, start, end) => p"StrOps.substring($expr, $start, $end)"