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Base-58 straw man implementation
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62
unison-src/base58.u
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62
unison-src/base58.u
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-- TODO: Characters
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-- TODO: Bytes
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type Optional a = Some a | None
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type Words = Words (Sequence UInt64)
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type Integer = Integer
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Integer.zero : Integer
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Integer.zero = _
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shiftLeft : UInt64 -> Integer -> Integer
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shiftLeft x y = _
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(+) : Integer -> Integer -> Integer
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(+) x y = _
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unfoldRight : ∀ a b . (a -> Optional (a, b)) -> a -> Sequence b
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unfoldRight f z = _
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foldLeft : ∀ a b . a -> (a -> b -> a) -> Sequence b -> a
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foldLeft z f s = _
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toInteger : UInt64 -> Integer
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toInteger x = _
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bigEndian : Words -> Integer
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bigEndian ws = case ws of
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Words.Words s ->
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foldLeft Integer.zero (acc w -> shiftLeft 8 acc + toInteger w) s
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-- TODO: Need some conversions between integers and machine integers
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divmod : Integer -> UInt64 -> (Integer, UInt64)
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divmod x y = _
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(|>) : ∀ a b c . (a -> b) -> (b -> c) -> a -> c
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(|>) g f x = f (g x)
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(==) : Integer -> UInt64 -> Boolean
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(==) a b = _
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charAt : UInt64 -> Text -> Text
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charAt n = Text.drop n |> Text.take 1
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codeString : Text
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codeString = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
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base58Encode : Words -> Text
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base58Encode ws =
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x = bigEndian ws
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base58 : Integer -> Optional (Integer, Text)
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base58 a =
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if a == 0
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then Optional.None
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else case divmod a 58 of
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(d, m) -> Optional.Some (d, charAt m codeString)
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foldLeft "" Text.concatenate (unfoldRight base58 x)
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base58Decode : Text -> Words
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base58Decode txt = _
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()
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