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90 lines
2.2 KiB
Plaintext
90 lines
2.2 KiB
Plaintext
app "prime"
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packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.1/Icc3xJoIixF3hCcfXrDwLCu4wQHtNdPyoJkEbkgIElA.tar.br" }
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imports [pf.Stdout, pf.Task, pf.Arg]
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provides [main] to pf
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main : Task.Task {} I32
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main =
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max <- Task.await parseArg
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numStrings =
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primesIn max
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|> List.map Num.toStr
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|> Str.joinWith "\n"
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Stdout.line "$(numStrings)"
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parseArg =
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args <- Task.await (Arg.list)
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arg =
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args
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|> List.get 1
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|> Result.withDefault "50_000_000"
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|> Str.toU64
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when arg is
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Ok a -> a |> Task.ok
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Err InvalidNumStr -> crash "Passed argument is not a numberr"
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primesIn : U64 -> List U64
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primesIn = \max ->
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filterPrimesRec = \acc, l ->
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when l is
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[] -> acc
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[head, .. as tail] if isPrimePost acc head ->
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acc |> List.append head |> filterPrimesRec tail
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[_, .. as tail] -> filterPrimesRec acc tail
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[2]
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|> List.concat (List.range { start: At 3u64, end: At max, step: 2 })
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|> \l -> filterPrimesRec [] l
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isPrimePost = \list, n ->
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isPrimeRec = \l, limit ->
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when l is
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[_] -> Bool.true
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[head, .. as tail] ->
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if Num.isMultipleOf n head then
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Bool.false
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else if head > limit then
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Bool.true
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else
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isPrimeRec tail limit
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[] -> Bool.true
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sqrtF = Num.sqrt (Num.toF32 n)
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sqrtI = Num.floor sqrtF
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if Num.isZero (sqrtF - Num.toF32 sqrtI) then
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Bool.false
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else
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isPrimeRec list (sqrtI + 1)
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countPrimesIn : U64 -> Nat
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countPrimesIn = \limit ->
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List.range { start: At 2, end: At limit }
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|> List.countIf \n ->
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if n < 4 then
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Bool.true
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else if Num.isEven n then
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Bool.false
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else
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List.range { start: At 3, end: At (Num.ceiling (Num.sqrt (Num.toF64 n))), step: 2 }
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|> List.any \a -> Num.isMultipleOf n a
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|> Bool.not
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expect
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(
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countPrimesIn 1000000
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|> \expected ->
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dbg expected
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expected
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)
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== (
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List.len (primesIn 1000000)
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|> \actual ->
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dbg actual
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actual
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)
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