samples: remove receiver.do, fix usable.do

samples/receiver.do

@@ -1,59 +0,0 @@
-#!/usr/bin/env dough
-
-/*
-Type = "type" Identifier (<Generics>)? '=' TypeSpec
-
-TypeSpec = (
-    | Identifier
-    | str (StructField),* uct
-    | tup (TupleField),*  le
-    | cho (ChoiceField),* ice
-)
-
-StructField = Identifier ':' TypeSpec
-TupleField = TypeSpec
-EnumField = Identifier ('(' TypeSpec ')')?
-
-*/
-
-// Product type with named fields
-type Product<T> = {
-    a: i32,
-    b: T,
-    c: {
-        d: i32,
-        e: i32,
-        f: []
-    },
-};
-
-// Product type with indexed fields
-type Tuple<T, U> = (
-    i32,
-    T,
-    U,
-);
-
-// Choice/Sum type, which degrades to enumeration
-type Sum = Nothing | A(Product) | B(Tuple) ;
-
-
-// Kotlin style?
-type <V> Option = {
-    None,
-    Some(V)
-}
-
-// fucked up?
-type Option<V> (None | Some(V));
-
-fn x(self: &Sum) -> Product {
-    match self {
-        Nothing | B(_) => panic(),
-        A(value) => 
-    }
-}
-
-fun x(a: T<A>) -> A {
-    a.get()
-}

samples/usable.do

@@ -1,6 +1,6 @@
 //! Sample doughlang code
 
-struct Expr {
+enum Expr {
     Atom (f64),
     Op (char, [Expr]),
 }