Funky Roman

1_python_reduceOnly.py

from functools import reduce

def convertToRoman(num):
    roman_factors = [(1000, 'M'), (900, 'CM'), (500, 'D'), (400, 'CD'), (100, 'C'), (90, 'XC'), (50, 'L'), (40, 'XL'), (10, 'X'), (9, 'IX'), (5, 'V'), (4, 'IV'), (1, 'I') ]
    return reduce(lambda state, factor: (state[0] % factor[0], state[1] + factor[1] * (state[0] // factor[0])), [(num, '')] + roman_factors)[1]


print(convertToRoman(2049))

2_fsharp_reduceOnly.fsx

let toRoman num =
    [
        num, ""
        1000, "M"
        900, "CM"
        500, "D"
        400, "CD"
        100, "C"
        90, "XC"
        50, "L"
        40, "XL"
        10, "X"
        9, "IX"
        5, "V"
        4, "IV"
        1, "I"
    ]
    |> List.reduce(fun (accMod,currentRes) (arabic,roman) ->
        accMod % arabic,
        currentRes + (String.replicate (accMod / arabic) roman))
    |> fun (_,res) -> res

toRoman 2049

3_fsharp_imperativ.fsx

let toRoman num =
    let romanFactors = [
        1000, "M"
        900, "CM"
        500, "D"
        400, "CD"
        100, "C"
        90, "XC"
        50, "L"
        40, "XL"
        10, "X"
        9, "IX"
        5, "V"
        4, "IV"
        1, "I"
    ]

    let mutable accMod = num
    let mutable currentRes = ""
    
    for (arabic,roman) in romanFactors do
        currentRes <- currentRes + (String.replicate (accMod / arabic) roman)
        accMod <- accMod % arabic

    currentRes

toRoman 2049

4_fsharp_semigroup_nonGeneric.fsx

type Semi = One of value : int | Many of last : int * result : int list

let moduloSemi a b =
    match a,b with
    | Many (x,res), One s -> let c = x % s in Many(c, res @ [c])
    | One s1, One s2 -> let c = s1 % s2 in Many(c, [c])

let result (Many (_,res)) = res

let toRoman num =

    // small helper for list ans string
    let exceptLast (l: _ list) = l.[.. l.Length - 2]
    let ( ** ) = String.replicate

    let factors = [
        1000, "M"
        900, "CM"
        500, "D"
        400, "CD"
        100, "C"
        90, "XC"
        50, "L"
        40, "XL"
        10, "X"
        9, "IX"
        5, "V"
        4, "IV"
        1, "I"
    ]

    factors
    |> List.map (fun (a,_) -> a)
    |> List.append [num]
    |> List.map One
    |> List.reduce moduloSemi
    |> (result >> exceptLast)
    |> List.append [num]
    |> List.zip factors
    |> List.map (fun ((arab,roman),accMod) -> (accMod / arab) ** roman)
    |> List.reduce (+)

toRoman 2049