1 files changed, 65 insertions, 0 deletions
diff --git a/src/pypeline/core/arrows/kleisli_arrow_choice.py b/src/pypeline/core/arrows/kleisli_arrow_choice.py
new file mode 100644
index 0000000..aba2d4e
--- /dev/null
+++ b/src/pypeline/core/arrows/kleisli_arrow_choice.py
@@ -0,0 +1,65 @@
+#
+# Copyright Applied Language Solutions 2012
+#
+# This file is part of Pypeline.
+#
+# Pypeline is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Pypeline is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Pypeline.  If not, see <http://www.gnu.org/licenses/>.
+#
+from pypeline.core.arrows.arrow import Arrow, ArrowChoice
+from pypeline.core.arrows.kleisli_arrow import KleisliArrow
+from pypeline.core.types.either import *
+
+
+class KleisliArrowChoice(ArrowChoice, KleisliArrow):
+    def __init__(self, patcher, f):
+        ArrowChoice.__init__(self)
+        KleisliArrow.__init__(self, patcher, f)
+
+    # left :: a b c -> a (Either b d) (Either c d)
+    def left(self):
+        def left_func(either):
+            if isinstance(either, Left):
+                return self._func(either.val) >= (lambda a: self._patcher(Left(a)))
+            elif isinstance(either, Right):
+                return self._patcher(either)
+            else:
+                raise ValueError("Must be of type Either")
+
+        return KleisliArrowChoice(self._patcher, left_func)
+
+    # right :: a b c -> a (Either d b) (Either d c)
+    def right(self):
+        def right_func(either):
+            if isinstance(either, Right):
+                return self._func(either.val) >= (lambda a: self._patcher(Right(a)))
+            elif isinstance(either, Left):
+                return self._patcher(either)
+            else:
+                raise ValueError("Must be of type Either")
+
+        return KleisliArrowChoice(self._patcher, right_func)
+
+    # (+++) :: a b c -> a b' c' -> a (Either b b') (Either c c')
+    def __add__(self, other):
+        if not isinstance(other, KleisliArrowChoice):
+            raise ValueError("Must be a KleisliArrowChoice")
+
+        return self.left() >> other.right()
+
+    # (|||) :: a b d -> a c d -> a (Either b c) d
+    def __or__(self, other):
+        if not isinstance(other, KleisliArrowChoice):
+            raise ValueError("Must be a KleisliArrowChoice")
+
+        return (self + other) >> KleisliArrow(other._patcher, lambda either: self._patcher(either.val))