Borrowing Books in CF

single_input :: IO ->> Int
Empty => Int IO.raw_input ""

double_input :: IO ->> (Int, Int)
Empty ~> {
    Empty => IO.raw_input "",
    raw => String.split raw " ",
    [a, b, ...c] => (Int a, Int b),
}

output_val :: Bool ->> IO
True => IO.log <- 1
False => IO.log <- 0

borrow :: [Int], Int, Int ->> [Int]
books, idx, dur => books[idx] = dur

day_passing :: [Int] ->> [Int]
books => @ (books''0 - 1)

available :: [Int], Int ->> Maybe Bool
book, idx | idx < 0 => Nothing
book, idx | idx > length book => Nothing
book, idx => book[idx] <= 0

do:
    nbBooks, nbDays = double_input ()
    books = fill [0..nbBooks] 0
    for day in [0..nbDays]:
        for c in [0..single_input ()]:
            idx, dur = double_input ()
            avail = available books idx
            IO.log <- output_val avail
            if avail:
                borrow books idx dur
        books = day_passing books