def __str__(self):
return 'Leaf %r' % self.value
def __repr__(self):
return 'Leaf %r' % self.value
class Branch(Tree):
def __init__(self, left, right):
self.left = left
self.right = right
def __str__(self):
return 'Branch (%r) (%r)' % (self.left, self.right)
def __repr__(self):
return 'Branch (%r) (%r)' % (self.left, self.right)
instance(Functor, Tree, lambda f, o: Leaf(f(o.value)) if isinstance(o, Leaf)
else Branch(fmap(f, o.left), fmap(f, o.right)))
instance(Eq, Tree,
lambda a, b:
a.value == b.value if (
isinstance(a, Leaf) and isinstance(b, Leaf))
else (eq(a.left, b.left) and eq(a.right, b.right)) if (
isinstance(a, Branch) and isinstance(b, Branch))
else False,
None)
# typeclasses, an educational implementation of Haskell-style type # classes, in Python # # Copyright (C) 2010 Nicolas Trangez <eikke eikke com> # # This library 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, version 2.1 # of the License. # # This library 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 this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, # MA 02110-1301 USA '''Typeclass instance definitions for the 'list' type''' from typeclasses import instance from typeclasses.functor import Functor from typeclasses.eq import Eq instance(Functor, list, map) instance(Eq, list, lambda a, b: a == b, None)
class _Nothing(Maybe):
def __str__(self):
return 'Nothing'
def __repr__(self):
return 'Nothing'
Nothing = _Nothing()
del _Nothing
class Just(Maybe):
def __init__(self, value):
self.value = value
def __str__(self):
return 'Just %r' % self.value
def __repr__(self):
return 'Just %r' % self.value
instance(Functor, Maybe, lambda f, o: Just(f(o.value))
if o is not Nothing else Nothing)
instance(
Eq, Maybe, lambda a, b: True if a is Nothing and b is Nothing else False
if a is Nothing or b is Nothing else True
if a.value == b.value else False, None)
# typeclasses, an educational implementation of Haskell-style type # classes, in Python # # Copyright (C) 2010 Nicolas Trangez <eikke eikke com> # # This library 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, version 2.1 # of the License. # # This library 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 this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, # MA 02110-1301 USA '''Typeclass instance definitions for the 'list' type''' from typeclasses import instance from typeclasses.functor import Functor from typeclasses.eq import Eq instance(Functor, list, map) instance(Eq, list, lambda a, b: a == b, None)
# typeclasses, an educational implementation of Haskell-style type # classes, in Python # # Copyright (C) 2010 Nicolas Trangez <eikke eikke com> # # This library 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, version 2.1 # of the License. # # This library 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 this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, # MA 02110-1301 USA '''Typeclass instance definitions for the 'function' type''' from typeclasses import instance from typeclasses.functor import Functor # We need a reference to the 'function' type to be able to register typeclass # instances function = type(lambda: None) instance(Functor, function, lambda f, o: lambda x: f(o(x)))
# typeclasses, an educational implementation of Haskell-style type # classes, in Python # # Copyright (C) 2010 Nicolas Trangez <eikke eikke com> # # This library 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, version 2.1 # of the License. # # This library 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 this library; if not, write to the Free Software # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, # MA 02110-1301 USA '''Typeclass instance definitions for the 'tuple' type''' from typeclasses import instance from typeclasses.functor import Functor from typeclasses.eq import Eq instance(Functor, tuple, lambda f, o: tuple(f(i) for i in o)) instance(Eq, tuple, None, lambda a, b: a != b)
class _Nothing(Maybe):
def __str__(self):
return 'Nothing'
def __repr__(self):
return 'Nothing'
Nothing = _Nothing()
del _Nothing
class Just(Maybe):
def __init__(self, value):
self.value = value
def __str__(self):
return 'Just %r' % self.value
def __repr__(self):
return 'Just %r' % self.value
instance(Functor, Maybe, lambda f, o: Just(f(o.value)) if o is not Nothing
else Nothing)
instance(Eq, Maybe,
lambda a, b: True if a is Nothing and b is Nothing else
False if a is Nothing or b is Nothing else
True if a.value == b.value else
False,
None)