Doc.

doc/tutorial/index.rst

@@ -10,7 +10,8 @@ Contents:
 .. toctree::
    :maxdepth: 2
 
-   tutorial 
+   hello 
+   pythagoras
 
 Indices and tables
 ==================

doc/tutorial/pythagoras.rst

@@ -0,0 +1,57 @@
+Pythagoras
+==========
+
+The ancient Greek mathematician Pythagoras is famous for
+the invariant of right angle triangles:
+
+.. math::
+
+    h ^ 2 = w^ 2 + a^2
+
+where `h` is the hypotenuse, `w` is the width of the base,
+and `a` is the altitute.
+
+We can calculate the hypotenuse in Felix like this:
+
+.. code-block:: felix
+
+    fun hypot (w:double, a:double) : double =>
+      sqrt (w^2 + a^2)
+    ;
+
+    println$ hypot (3.0, 4.0);
+
+The type `double` is a standard double precision floating point real
+number. 
+
+The `sqrt` function is in the library, and calculates the
+square root of a double precision number.
+
+The operator `^` denotes exponentiation, in this case
+we are squaring, or muliplying the argument by itself twice,
+the literal `2` is a value of type `int`, a type of small
+integers.
+
+Of course, the operator `+` is addition.
+
+The `fun` binder is used here to define a function. Then we give
+the function name we want to use, in this case `hypot`.
+
+Then, in paranthesis we give a comma separated list of paramater
+specifications. Each specification is the name of the parameter,
+followed by its type.
+
+It is good practice, but not required, to follow the parameters
+with `:` and the return type of the function. 
+
+Then the `=>` symbol is used to begin the formula defining the function
+in terms of the parameters.
+
+The function can be used by applying it to an argument of the 
+correct type,  in this case a pair, or tuple, of two numbers
+of type `double`. 
+
+The `println` is then called on the application using
+the application operator `$`.
+
+

src/packages/fibres.fdoc

@@ -308,6 +308,10 @@ open class Schannel
     var ps = C_hack::cast[root::address]$ new v;
     svc$ svc_swrite$ C_hack::cast[_schannel] chan, &ps;
   }
+
+  proc write[T] (chan:oschannel[T], v:T) { 
+    write (C_hack::cast[schannel[T]] chan, v); 
+  }
 
   //$ Multi Write an item to a bidirectional channel.
   proc broadcast[T] (chan:schannel[T], v:T) {
@@ -316,9 +320,6 @@ open class Schannel
   }
 
   //$ Multi Write an item to an output channel.
-  proc write[T] (chan:oschannel[T], v:T) { 
-    write (C_hack::cast[schannel[T]] chan, v); 
-  }
   proc broadcast[T] (chan:oschannel[T], v:T) { 
     broadcast (C_hack::cast[schannel[T]] chan, v); 
   }