base58 by @9214

base58_9214.red

unfold: function [spec][
    to string! collect [
        repeat i length? bitset: charset spec [
            if bitset/:i [keep to char! i]
        ]
    ]
]

to-base58: function [string][
    base58: rejoin [
        exclude unfold [#"0" - #"9"] "0"
        exclude unfold [#"A" - #"Z"] "IO"
        exclude unfold [#"a" - #"z"] "l"
    ]

    acc: 0
    repeat i length: length? string [
        index:  length - i
        factor: 2.0 ** (index * 8)
        acc:    acc + multiply to float! string/:i factor
    ]

    to string! collect [
        foreach index reverse collect [
            until [
                probe acc
                keep add to integer! probe (acc % 58) 1
                zero? round acc: acc / 58
            ]
        ][
            keep base58/:index
        ]
    ]
]