Stern-Brocot sequence: Difference between revisions
→Python: Composing pure (curried) functions: Updated primitives.
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(→Python: Composing pure (curried) functions: Updated primitives.) |
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<lang python>'''Stern-Brocot sequence'''
import math▼
from itertools import (count, dropwhile, islice, takewhile)▼
import operator
▲import math
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def go(xs):
x = xs[1]
return (x, tail(xs) + [x + head(xs), x])
return
)▼
# TESTS ---------------------------------------------------▼
# main :: IO ()
def main():
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#
# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
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'''True if p(x) holds for every x in xs'''
return lambda xs: all(map(p, xs))
# fmapGen <$> :: (a -> b) -> Gen [a] -> Gen [b]▼
def fmapGen(f):▼
def go(g):▼
while True:▼
yield f(v)▼
return lambda gen: go(gen)▼
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'''The first element of a non-empty list.'''
return xs[0]
v = x▼
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'''A sublist of xs from which all duplicates,
(as defined by the equality predicate p)
are excluded.
def go(xs):
if not xs:
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))
)
return
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return xs[1:]
else:
return xs
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else list(islice(xs, n))
)
'''A lazy (generator) list unfolded from a seed value
by repeated application of f until no residue remains.
Dual to fold/reduce.
f returns either None or just (value, residue).
For a strict output list, wrap the result with list()
'''
valueResidue = f(valueResidue[1])
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