From 6749e5dd658522cb63600021a9ee5a86f911cfeb Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 3 Mar 2003 14:33:53 +0000
Subject: *** empty log message ***

---
 sources/examples/fors.scala | 63 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 sources/examples/fors.scala

(limited to 'sources/examples/fors.scala')

diff --git a/sources/examples/fors.scala b/sources/examples/fors.scala
new file mode 100644
index 0000000000..55849f4010
--- /dev/null
+++ b/sources/examples/fors.scala
@@ -0,0 +1,63 @@
+module fors {
+
+  trait Person {
+    val name: String;
+    val age: Int;
+  }
+
+  def printOlderThan20(xs: Seq[Person]): Iterator[String] =
+    printOlderThan20(xs.elements);
+
+  def printOlderThan20(xs: Iterator[Person]): Iterator[String] =
+    for (val p <- xs; p.age > 20) yield p.name;
+
+  def divisors(n: Int): List[Int] =
+    for (val i <- List.range(1, n); n % i == 0) yield i;
+
+  def isPrime(n: Int) = divisors(n).length == 2;
+
+  def findNums(n: Int): Iterator[Pair[Int, Int]] =
+    for (val i <- Iterator.range(1, n);
+         val j <- Iterator.range(1, i-1);
+         isPrime(i+j)) yield Pair(i, j);
+
+  def sum(xs: List[Double]): Double =
+    (0.0 foldl_: xs) { (x, y) => x + y }
+
+  def scalProd(xs: List[Double], ys: List[Double]) =
+    sum(for(val Pair(x, y) <- xs zip ys) yield x * y);
+
+  type Lst = List[Any];
+
+  val books = List(
+    'book('title("Structure and Interpretation of Computer Programs"),
+          'author("Abelson, Harald"),
+          'author("Sussman, Gerald J.")),
+    'book('title("Principles of Compiler Design"),
+          'author("Aho, Alfred"),
+          'author("Ullman, Jeffrey")),
+    'book('title("Programming in Modula-2"),
+	  'author("Wirth, Niklaus")));
+
+  def findAuthor(books: Lst) =
+    for (val 'book(book: Lst) <- books;
+         val 'title(title: String) <- book;
+         (title indexOf "Program") >= 0;
+         val 'author(author: String) <- book) yield author;
+
+  for (val 'book(b: Lst) <- books;
+       val 'author(author: String) <- b;
+       author startsWith "Ullman";
+       val 'title(title: String) <- b) yield title;
+
+  removeDuplicates(
+    for (val 'book(b1: Lst) <- books;
+       val 'book(b2: Lst) <- books;
+	 b1 != b2;
+	 val 'author(a1: String) <- b1;
+	 val 'author(a2: String) <- b2;
+	 a1 == a2) yield Pair(a1, a2));
+
+  def removeDuplicates[a](xs: List[a]): List[a] =
+    xs.head :: removeDuplicates(for (val x <- xs.tail; x != xs.head) yield x)
+}
-- 
cgit v1.2.3