Expression?

implementations/Python/joy/expr.py

@@ -0,0 +1,25 @@
+
+
+class Expression:
+
+    def __init__(self, initial_expression=()):
+        self.current = initial_expression
+        self.stack = []
+
+    def __next__(self):
+        if self.current:
+            item, self.current = self.current
+            return item
+        if self.stack:
+            self.current = self.stack.pop()
+            return self.__next__()
+        raise StopIteration
+
+    def prepend(self, quoted_program):
+        if self.current:
+            self.stack.append(self.current)
+        self.current = quoted_program
+
+
+from parser import text_to_expression as j
+e = Expression(j('23 18'))