# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1481393106 -3600
# Node ID 2ab8235da0608202ee225b24dad1d23d30850fb8
# Parent  2eb43643f5eddd59b24753eba21ac5cc8cc7fce6
Implemented enumerate, filter, map, reversed and sum. Fixed max and min.
Extended the tests to cover these functions.

diff -r 2eb43643f5ed -r 2ab8235da060 lib/__builtins__/iterable.py
--- a/lib/__builtins__/iterable.py	Sat Dec 10 18:54:07 2016 +0100
+++ b/lib/__builtins__/iterable.py	Sat Dec 10 19:05:06 2016 +0100
@@ -21,8 +21,39 @@
 
 def all(iterable): pass
 def any(iterable): pass
-def enumerate(iterable): pass
-def filter(function, sequence): pass
+
+def enumerate(iterable, start=0):
+
+    """
+    Iterate over 'iterable', obtaining items and combining them with position
+    information, producing a sequence containing tuples of the form
+    (position, item). The first position is indicated by 'start' (which is zero
+    by default) and each subsequent positions is incremented from the one
+    preceding it.
+    """
+
+    l = []
+    pos = start
+
+    for i in iterable:
+        l.append((pos, i))
+        pos += 1
+
+    return l
+
+def filter(function, sequence):
+
+    """
+    Apply 'function' to each element in 'sequence', returning a sequence of all
+    elements for which the result of the function evaluated to a true value.
+    """
+
+    l = []
+    for i in sequence:
+        if function(i):
+            l.append(i)
+    return l
+
 def iter(collection):
 
     "Implementation of iter without callable plus sentinel support."
@@ -35,32 +66,56 @@
 
     return obj.__len__()
 
-def map(function, *args): pass
+def map(function, sequence):
+
+    """
+    Apply 'function' to each element of 'sequence' in turn, appending the result
+    to a new sequence containing all results.
+    """
 
-def max(*args):
+    l = []
+    for i in sequence:
+        l.append(function(i))
+    return l
+
+def max(args):
 
     "Implementation of max."
 
-    highest = args[0]
-    for arg in args[1:]:
-        if arg > highest:
+    highest = None
+    for arg in args:
+        if highest is None or arg > highest:
             highest = arg
     return highest
 
-def min(*args):
+def min(args):
 
     "Implementation of min."
 
-    lowest = args[0]
-    for arg in args[1:]:
-        if arg > lowest:
+    lowest = None
+    for arg in args:
+        if lowest is None or arg < lowest:
             lowest = arg
     return lowest
 
 def reduce(function, sequence, initial=None): pass
-def reversed(sequence): pass
+
+def reversed(sequence):
+
+    "Return a reversed version of the given 'sequence'."
+
+    return sequence[::-1]
+
 def sorted(iterable, cmp=None, key=None, reverse=False): pass
-def sum(sequence, start=0): pass
+
+def sum(sequence, start=0):
+
+    "Sum the elements in 'sequence', adding to any indicated 'start' value."
+
+    total = start
+    for i in sequence:
+        total += i
+    return total
 
 def zip(args):
 
diff -r 2eb43643f5ed -r 2ab8235da060 tests/range.py
--- a/tests/range.py	Sat Dec 10 18:54:07 2016 +0100
+++ b/tests/range.py	Sat Dec 10 19:05:06 2016 +0100
@@ -1,18 +1,27 @@
 l = range(0, 10)
-print l                     # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
-print len(l)                # 10
+print l                         # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+print len(l)                    # 10
 
 x = xrange(0, -10, -2)
-print x                     # __builtins__.span.xrange(0, -10, -2)
-print len(x)                # 5
+print x                         # __builtins__.span.xrange(0, -10, -2)
+print len(x)                    # 5
 
 for i in x:
-    print i                 # 0
-                            # -2
-                            # -4
-                            # -6
-                            # -8
+    print i                     # 0
+                                # -2
+                                # -4
+                                # -6
+                                # -8
 
 x = xrange(0, -10, 2)
-print x                     # __builtins__.span.xrange(0, 0, 2)
-print len(x)                # 0
+print x                         # __builtins__.span.xrange(0, 0, 2)
+print len(x)                    # 0
+
+y = xrange(4, 8)
+print y                         # __builtins__.span.xrange(4, 8, 1)
+print enumerate(y)              # [(0, 4), (1, 5), (2, 6), (3, 7)]
+print sum(y)                    # 22
+print map(lambda x: x*2, y)     # [8, 10, 12, 14]
+print filter(lambda x: x%2, y)  # [5, 7]
+print max(y)                    # 7
+print min(y)                    # 4
diff -r 2eb43643f5ed -r 2ab8235da060 tests/slice.py
--- a/tests/slice.py	Sat Dec 10 18:54:07 2016 +0100
+++ b/tests/slice.py	Sat Dec 10 19:05:06 2016 +0100
@@ -11,3 +11,5 @@
 print l[1:9:2]              # [1, 3, 5, 7]
 print l[9:1:-2]             # [9, 7, 5, 3]
 print l[::-1]               # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
+print l[::-2]               # [9, 7, 5, 3, 1]
+print reversed(l)           # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]