updated from Atlas repo

iterables/aritprog_v2.py

@@ -1,32 +1,31 @@
 """
-Arithmetic progression class
+Arithmetic progression generator function::
 
-    >>> ap = ArithmeticProgression(1, .5, 3)
+    >>> ap = aritprog_gen(1, .5, 3)
     >>> list(ap)
     [1.0, 1.5, 2.0, 2.5]
-
+    >>> ap = aritprog_gen(0, 1/3, 1)
+    >>> list(ap)
+    [0.0, 0.3333333333333333, 0.6666666666666666]
+    >>> from fractions import Fraction
+    >>> ap = aritprog_gen(0, Fraction(1, 3), 1)
+    >>> list(ap)
+    [Fraction(0, 1), Fraction(1, 3), Fraction(2, 3)]
+    >>> from decimal import Decimal
+    >>> ap = aritprog_gen(0, Decimal('.1'), .3)
+    >>> list(ap)
+    [Decimal('0.0'), Decimal('0.1'), Decimal('0.2')]
 
 """
 
-import array
-from collections import abc
 
-class ArithmeticProgression:
-
-    def __init__(self, begin, step, end):
-        self.begin = begin
-        self.step = step
-        self.end = end
-        self._build()
-
-    def _build(self):
-        self._numbers = array.array('d')
-        n = self.begin
-        while n < self.end:
-            self._numbers.append(n)
-            n += self.step
-
-    def __iter__(self):
-        for item in self._numbers:
-            yield item
-        return StopIteration
+# BEGIN ARITPROG_GENFUNC
+def aritprog_gen(begin, step, end=None):
+    result = type(begin + step)(begin)
+    forever = end is None
+    index = 0
+    while forever or result < end:
+        yield result
+        index += 1
+        result = begin + step * index
+# END ARITPROG_GENFUNC