def test_build_chessboard():
# shamelessly stolen from:
# https://github.com/dustingetz/pymonads/blob/master/list.py
ranks = 'abcdefg'
files = range(1, 9)
l = List(*ranks) >> (lambda r: List(*files) >> (lambda f: List.unit(
(r, f))))
hardway = tuple((r, f) for r in ranks for f in files)
sliced = List(('a', 1), ('a', 2), ('a', 3))
assert l.v == hardway
assert l[:3] == sliced
def test_writer_bind():
w = Writer.unit(2) >> m_add_two
assert w.v == (4, List.unit('added two'))
from pynads import Writer, Mempty, List
from pynads.funcs import identity, multibind
import pytest
add_two = lambda x: x + 2
m_add_two = lambda x: Writer(x + 2, List.unit('added two'))
str_add_two = lambda x: Writer(add_two(x), ' added two')
int_add_two = lambda x: Writer(add_two(x), 4)
dict_add_two = lambda x: Writer(add_two(x), {'added': 2})
dict_div_two = lambda x: Writer(x // 2, {'divided': 2})
def test_writer_unit():
w = Writer.unit(2)
assert w.v == (2, Mempty)
def test_fmap_id():
w = Writer.unit(2).fmap(identity)
assert w.v == (2, Mempty)
def test_writer_fmap():
w = Writer.unit(2).fmap(add_two)
assert w.v == (4, Mempty)
def test_writer_apply():
w = (Writer.unit(add_two)) * (Writer.unit(2))
assert w.v == (4, Mempty)
def test_List_unit():
assert List.unit(1).v == (1, )
assert List.unit('fred').v == ('fred', )
assert List.unit([1, 2, 3]).v == ([1, 2, 3], )
def test_List_is_monoidal():
ls = [List.unit(x) for x in [1, 2, 3]]
assert List.mappend(ls[0], List.mappend(ls[1], ls[2])) == \
List.mappend(List.mappend(ls[0], ls[1]), ls[2])
def test_List_mconcat():
ls = [List.unit(x) for x in range(4)]
final = List.mconcat(*ls)
assert final == List(0, 1, 2, 3)
def test_List_monoidal_add():
l = List.unit(1)
assert l + (List.unit(2)) == List(1, 2)
assert l + (2, ) == List(1, 2)
def test_List_iadd():
l1 = l2 = List.unit(1)
l1 += List.unit(2)
assert l1 == List(1, 2)
assert l1 is not l2
def test_List_eq():
assert List(1, 2, 3) == List(1, 2, 3)
assert List.unit(1) != List(1, 2)
