Fibonacci sequence

editable example

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Functional

ghul

use IO.Std.write_line

use Ghul.Pipes

let fibonacci_sequence = stream(

(0, 1),

((previous, current)) =>

previous || (current, previous + current)

)

let fib = n => fibonacci_sequence |> skip(n) |> first()

fibonacci_sequence

|> take(10)

|> index()

|> each(((position, value)) =>

write_line("fib({position}) = {value}"))

write_line("fib(30) = {fib(30)}")

fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(30) = 832040

Imperative

ghul

use IO.Std.write_line

use Ghul.Pipes

fibonacci() -> Pipe[int] is

let previous mut = 0

let current mut = 1

do

yield previous

(previous, current) = (current, previous + current)

od

si

let fib = n => fibonacci() |> skip(n) |> first()

for (position, value) in fibonacci() |> take(10) |> index() do

write_line("fib({position}) = {value}")

od

write_line("fib(30) = {fib(30)}")

fib(0) = 0
fib(1) = 1
fib(2) = 1
fib(3) = 2
fib(4) = 3
fib(5) = 5
fib(6) = 8
fib(7) = 13
fib(8) = 21
fib(9) = 34
fib(30) = 832040