Negative base numbers
editable example
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ghul
use IO.Std.write_line
use Ghul.Pipes
let digit_set = "0123456789abcdefghijklmnopqrstuvwxyz"
encode(n: int, base: int) -> string => (
let rest mut = n
let digits mut = ""
while rest != 0 do
let remainder mut = rest % base
rest = rest / base
if remainder < 0 then
remainder = remainder - base
rest = rest + 1
fi
digits = "{digit_set[remainder]}{digits}"
od
if digits.length == 0 then "0" else digits fi
)
decode(encoded: string, base: int) -> int =>
encoded
|> reduce(0, (value, digit) =>
value * base + digit_set.index_of(digit))
for (n, base) in [(10, -2), (146, -3), (15, -10)] do
let encoded = encode(n, base)
write_line(
"{n} in base {base} is {encoded}, "
"and back again is {decode(encoded, base)}")
od