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import gleam/list
import gleam/int
import gleam/io
import gleam/result
import gleam/erlang.{start_arguments}
fn get_day(handler: fn(Int) -> Nil) -> Result(Nil, String) {
let args = start_arguments()
use first <- result.then(
args
|> list.first()
|> result.replace_error("Pass the day as first argument!"),
)
use day <- result.then(
first
|> int.parse()
|> result.replace_error("The day argument must be a number!"),
)
handler(day)
Ok(Nil)
}
pub fn with_day(handler: fn(Int) -> Nil) -> Nil {
handler
|> get_day()
|> result.map_error(io.println)
|> result.unwrap(Nil)
}
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