first "OK" closure test.

stdlib/src/jet/ExtensionFunction0.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class ExtensionFunction0<E, R> {
+    public abstract R invoke(E receiver);
+
+    @Override
+    public String toString() {
+        return "{E.() : R}";
+    }
+}

stdlib/src/jet/ExtensionFunction1.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class ExtensionFunction1<E, D, R> {
+    public abstract R invoke(E receiver, D d);
+
+    @Override
+    public String toString() {
+        return "{E.(d: D) : R}";
+    }
+}

stdlib/src/jet/ExtensionFunction2.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class ExtensionFunction2<E, D1, D2, R> {
+    public abstract R invoke(E receiver, D1 d1, D2 d2);
+
+    @Override
+    public String toString() {
+        return "{E.(d1: D1, d2: D2) : R}";
+    }
+}

stdlib/src/jet/ExtensionFunction3.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class ExtensionFunction3<E, D1, D2, D3, R> {
+    public abstract R invoke(E receiver, D1 d1, D2 d2, D3 d3);
+
+    @Override
+    public String toString() {
+        return "{E.(d1: D1, d2: D2, d3: D3) : R}";
+    }
+}

stdlib/src/jet/Function0.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class Function0<R> {
+    public abstract R invoke();
+
+    @Override
+    public String toString() {
+        return "{() : R}";
+    }
+}

stdlib/src/jet/Function1.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class Function1<D, R> {
+    public abstract R invoke(D d);
+
+    @Override
+    public String toString() {
+        return "{(d: D) : R}";
+    }
+}

stdlib/src/jet/Function2.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class Function2<D1, D2, R> {
+    public abstract R invoke(D1 d1, D2 d2);
+
+    @Override
+    public String toString() {
+        return "{(d1: D1, d2: D2) : R}";
+    }
+}

stdlib/src/jet/Function3.java

@@ -0,0 +1,13 @@
+/*
+ * @author max
+ */
+package jet;
+
+public abstract  class Function3<D1, D2, D3, R> {
+    public abstract R invoke(D1 d1, D2 d2, D3 d3);
+
+    @Override
+    public String toString() {
+        return "{(d1: D1, d2: D2, d3: D3) : R}";
+    }
+}