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--- at:tutorial:basic [2007/04/04 11:51] – * elisag
+++ at:tutorial:basic [2007/04/05 09:59] – elisag
@@ Line 73: / Line 73: @@
 >>25
 </code>
-Functions can call themselves recusively and as in Pico, functions can also be nested in the definitions other functions such as:
+This example also illustrates how functions are called. Calls to functions without parameters must also include the parenthesis.
+Functions have access to the enclosing environment of its definition as shown in the following example.
+<code>
+>def counter := 0
+>>0
+> def inc() { counter := counter + 1}
+>><closure:inc>
+>inc()
+>>1
+</code>
+Functions can call themselves recusively and they can also be nested in the definitions of other functions such as:
 <code>
 >def fac(n) {
@@ Line 81: / Line 93: @@
   inner(n,1)
 }
->>nil
+>><closure:fac>
 >fac(5)
 >>120
 </code>
-Variables and other functions defined locally to a function are only visible in the scope of the function where there were defined.
+Variables and functions defined locally to functions are only visible in the scope of the function where there were defined.  In the previous example, //fac// uses a local function //inner// that is only visible inside //fac// and its nested scopes, in the example //fac.inner.//
+=== Variable-Length Argument Functions ===
+You can create functions that take an arbitrary  number of arguments by means of the splicing operator **@** as shown below:
+<code>
+>def sum(@args){ {
+  def total := 0;
+  foreach: { |el|  total := total + el } in: args;
+  total}
+>><closure:sum>
+>sum(1,2,3)
+>>6
+</code>
+When the //sum// function is called, the arguments are passed to the function in a table called //args// which can also be modified inside the body of the function. An alternative definition of the //sum// function follows:
+<code>
+>def sum(a, b, @rest){ {
+  def total := a + b;
+  foreach: { |el|  total := total + el } in: rest;
+  total}
+>><closure:sum>
+>sum(1,2,3)
+>>6
+</code>
+In this example the //sum// function accepts an arbitrary number of arguments as long as two arguments, //a// and //b//, are supplied. //a// and //b// are thus considered as mandatory arguments. A function can also declare optional arguments as shown below:
+<code>
+>def incr( number, step := 1){ number + step}
+>><closure:incr>
+>incr(3)
+>>4
+>incr(3,3)
+>>6
+</code>
+==== Closures and Blocks ====
 The function name can also be used just to refer the function but without calling it. TODO!