Finish compose.py.

resources/python/compose.py

@@ -1,30 +1,57 @@
+import collections
 import functools
 
-
-def compose2(f, g):
-    return lambda x: f(g(x))
+from partialable import n_partialable
 
 
-def compose(*functions):
-    return reduce(compose2, functions)
+def _compose2(f, g):
+    return lambda *args, **kwargs: f(g(*args, **kwargs))
 
 
-def extract_args(function):
+@n_partialable(evaluation_checker=n_partialable.count_evaluation_checker(2))
+def compose_with_joiner(joiner, *functions):
+    return reduce(joiner, functions)
+
+
+compose_one_arg = compose_with_joiner(_compose2)
+
+
+compose = compose_with_joiner(lambda f, g: _compose2(make_single_arity(f),
+                                                force_args_return(g)))
+
+
+def make_single_arity(function):
     @functools.wraps(function)
     def wrapped(args):
         return function(*args)
     return wrapped
 
 
-def extract_kwargs(function):
+def kwargs_make_single_arity(function):
     @functools.wraps(function)
     def wrapped(kwargs):
         return function(**kwargs)
     return wrapped
 
 
-def extract_args_kwargs(function):
+def args_kwargs_make_single_arity(function):
     @functools.wraps(function)
     def wrapped((args, kwargs)):
         return function(*args, **kwargs)
     return wrapped
+
+
+def force_args_return(function):
+    @functools.wraps(function)
+    def wrapped(*args, **kwargs):
+        value = function(*args, **kwargs)
+        if not isinstance(value, collections.Iterable):
+            value = (value,)
+        return value
+    return wrapped
+
+
+def tee(*functions):
+    def wrapped(*args, **kwargs):
+        return tuple(function(*args, **kwargs) for function in functions)
+    return wrapped

resources/python/compose_test.py

@@ -0,0 +1,12 @@
+import compose
+
+
+def test_compose_handles_multiple_argument_output_and_non_iterable_output():
+    assert compose.compose(lambda x: x*2,
+                           lambda x, y: x + y,
+                           lambda x, y, z: (2*(x - y), z))(1, 2, 3) == 2
+
+
+def test_tee():
+    assert compose.compose(lambda x, y: x + y,
+                           compose.tee(lambda x: x + 1, lambda x: x - 1))(2) == 4

resources/python/partialable.py

@@ -4,10 +4,13 @@ import inspect
 class n_partialable(object):
 
     @staticmethod
-    def arity_evaluation_checker(function):
+    def arity_evaluation_checker(function, is_method=False):
+        is_class = inspect.isclass(function)
+        if is_class:
+            function = function.__init__
         function_info = inspect.getargspec(function)
         function_args = function_info.args
-        if inspect.isclass(function):
+        if is_class or is_method:
             # This is to handle the fact that self will get passed in automatically.
             function_args = function_args[1:]
         def evaluation_checker(*args, **kwargs):
@@ -21,10 +24,17 @@ class n_partialable(object):
             return not needed_args or kwarg_keys.issuperset(needed_args)
         return evaluation_checker
 
-    def __init__(self, function, evaluation_checker=None, args=None, kwargs=None):
+    @staticmethod
+    def count_evaluation_checker(count):
+        def function(*args, **kwargs):
+            return len(args) >= count
+        return function
+
+    def __init__(self, function, evaluation_checker=None, args=None, kwargs=None,
+                 is_method=False):
         self.function = function
         self.evaluation_checker = (evaluation_checker or
-                                   self.arity_evaluation_checker(function))
+                                   self.arity_evaluation_checker(function, is_method))
         self.args = args or ()
         self.kwargs = kwargs or {}