A collection of utilities to help write python as though it were an ML-kind of functional language like OCaml
The API is still unstable. Use at your own risk.
Documentation: https://sopherapps.github.io/funml
Source Code: https://github.com/sopherapps/funml
Most Notable Features are:
- Immutable data structures like enums, records, lists
- Piping outputs of one function to another as inputs. That's how bigger functions are created from smaller ones.
- Pattern matching for declarative conditional control of flow instead of using 'if's
- Error handling using the
Resultmonad, courtesy of rust. Instead of usingtry-exceptall over the place, functions return aResultwhich has the right data when successful and an exception if unsuccessful. The result is then pattern-matched to retrieve the data or react to the exception. - No
None. Instead, we use theOptionmonad, courtesy of rust. When an Option has data, it isOption.SOME, or else it isOption.NONE. Pattern matching helps handle both scenarios.
- Ensure you have python 3.7 and above installed.
- Install
FunML
pip install funml- Add the following code in
main.py
from copy import copy
from datetime import date
import funml as ml
class Date(ml.Enum):
January = date
February = date
March = date
April = date
May = date
June = date
July = date
August = date
September = date
October = date
November = date
December = date
@ml.record
class Color:
r: int
g: int
b: int
a: int
def main():
"""Main program"""
"""
Primitive Expressions
"""
unit = ml.val(lambda v: v)
is_even = ml.val(lambda v: v % 2 == 0)
mul = ml.val(lambda args: args[0] * args[1])
superscript = ml.val(lambda num, power=1: num**power)
get_month = ml.val(lambda value: value.month)
is_num = ml.val(lambda v: isinstance(v, (int, float)))
is_exp = ml.val(lambda v: isinstance(v, BaseException))
if_else = lambda check=unit, do=unit, else_do=unit: ml.val(
lambda *args, **kwargs: (
ml.match(check(*args, **kwargs))
.case(True, do=lambda: do(*args, **kwargs))
.case(False, do=lambda: else_do(*args, **kwargs))
)()
)
"""
High Order Expressions
"""
factorial = lambda v, accum=1: (
ml.match(v <= 0)
.case(True, do=ml.val(accum))
.case(False, do=lambda num, ac=0: factorial(num - 1, accum=num * ac)())
)
# currying expressions is possible
cube = superscript(power=3)
get_item_types = ml.ireduce(lambda x, y: f"{type(x)}, {type(y)}")
nums_type_err = ml.val(
lambda args: TypeError(f"expected numbers, got {get_item_types(args)}")
)
is_seq_of_nums = ml.ireduce(lambda x, y: x and is_num(y), True)
to_result = ml.val(lambda v: ml.Result.ERR(v) if is_exp(v) else ml.Result.OK(v))
try_multiply = (
if_else(check=is_seq_of_nums, do=mul, else_do=nums_type_err) >> to_result
)
result_to_option = ml.if_ok(ml.Option.SOME, strict=False) >> ml.if_err(
lambda *args: ml.Option.NONE, strict=False
)
to_date_enum = ml.val(
lambda v: (
ml.match(v.month)
.case(1, do=ml.val(Date.January(v)))
.case(2, do=ml.val(Date.February(v)))
.case(3, do=ml.val(Date.March(v)))
.case(4, do=ml.val(Date.April(v)))
.case(5, do=ml.val(Date.May(v)))
.case(6, do=ml.val(Date.June(v)))
.case(7, do=ml.val(Date.July(v)))
.case(8, do=ml.val(Date.August(v)))
.case(9, do=ml.val(Date.September(v)))
.case(10, do=ml.val(Date.October(v)))
.case(11, do=ml.val(Date.November(v)))
.case(12, do=ml.val(Date.December(v)))
)()
)
get_month_str = get_month >> (
ml.match()
.case(1, do=ml.val("JAN"))
.case(2, do=ml.val("FEB"))
.case(3, do=ml.val("MAR"))
.case(4, do=ml.val("APR"))
.case(5, do=ml.val("MAY"))
.case(6, do=ml.val("JUN"))
.case(7, do=ml.val("JUL"))
.case(8, do=ml.val("AUG"))
.case(9, do=ml.val("SEP"))
.case(10, do=ml.val("OCT"))
.case(11, do=ml.val("NOV"))
.case(12, do=ml.val("DEC"))
)
"""
Data
"""
dates = [
date(200, 3, 4),
date(2009, 1, 16),
date(1993, 12, 29),
date(2004, 10, 13),
date(2020, 9, 5),
date(2004, 5, 7),
date(1228, 8, 18),
]
dates = ml.val(dates)
nums = ml.val(ml.l(12, 3, 45, 7, 8, 6, 3))
data = ml.l((2, 3), ("hey", 7), (5, "y"), (8.1, 6))
blue = Color(r=0, g=0, b=255, a=1)
"""
Pipeline Creation and Execution
"""
dates_as_enums = dates >> ml.imap(to_date_enum) >> ml.execute()
print(f"\ndates as enums: {dates_as_enums}")
print(f"\nfirst date enum: {dates_as_enums[0]}")
months_as_str = dates >> ml.imap(get_month_str) >> ml.execute()
print(f"\nmonths of dates as str:\n{months_as_str}")
print(f"\ncube of 5: {cube(5)}")
even_nums_pipeline = nums >> ml.ifilter(is_even)
# here `even_nums_pipeline` is a `Pipeline` instance
print(even_nums_pipeline)
factorials_list = (
copy(even_nums_pipeline)
>> ml.imap(lambda v: f"factorial for {v}: {factorial(v)}")
>> ml.execute()
)
# we created a new pipeline by coping the previous one
# otherwise we would be mutating the old pipeline.
# Calling ml.execute(), we get an actual iterable of strings
print(factorials_list)
factorials_str = (
even_nums_pipeline
>> ml.imap(lambda v: f"factorial for {v}: {factorial(v)}")
>> ml.ireduce(lambda x, y: f"{x}\n{y}")
>> ml.execute()
)
# here after calling ml.execute(), we get one string as output
print(factorials_str)
print(f"blue: {blue}")
data = ml.val(data) >> ml.imap(try_multiply) >> ml.execute()
print(f"\nafter multiplication:\n{data}")
data_as_options = ml.val(data) >> ml.imap(result_to_option) >> ml.execute()
print(f"\ndata as options: {data_as_options}")
data_as_actual_values = (
ml.val(data) >> ml.ifilter(ml.is_ok) >> ml.imap(ml.if_ok(unit)) >> ml.execute()
)
print(f"\ndata as actual values: {data_as_actual_values}")
if __name__ == "__main__":
main()- Run the script
python main.py- For more details, visit the docs
Contributions are welcome. The docs have to maintained, the code has to be made cleaner, more idiomatic and faster, and there might be need for someone else to take over this repo in case I move on to other things. It happens!
Please look at the CONTRIBUTIONS GUIDELINES
Licensed under both the MIT License
Copyright (c) 2023 Martin Ahindura
"...and His (the Father's) incomparably great power for us who believe. That power is the same as the mighty strength He exerted when He raised Christ from the dead and seated Him at His right hand in the heavenly realms, far above all rule and authority, power and dominion, and every name that is invoked, not only in the present age but also in the one to come."
-- Ephesians 1: 19-21
All glory be to God.
