tote

👜 Bags (or multisets) in Gleam

⚙️ This package works for both the Erlang and JavaScript target

What’s a bag?

A Bag is a data structure similar to a set with the difference that it can store multiple copies of the same item.

This means that you can efficiently check if an element is inside a bag with the contains function, just like a set. At the same time, you can ask how many copies of an item are contained inside a bag using the copies function.

If you are curious about implementation details, a Bag(a) is nothing more than a handy wrapper around a Map(a, Int) that is used to keep track of the number of occurrences of each item.

Installation

To add this package to your Gleam project:

gleam add tote

Getting started

All the bag-related functions are in the tote/bag module, so once you’ve imported that you’re good to go:

import gleam/int
import gleam/io
import tote/bag

pub fn main() {
  let valentino_bag =
    bag.from_list([
      "lipstick", "in", "my", "wh-", "wh-", "lipstick",
      "in", "my", "Valentino", "white", "bag", "?!"
    ])

  bag.copies(of: "lipstick", in: valentino_bag)
  |> int.to_string
  |> io.println
  // -> 2
}

If you don’t get the Valentino reference, you’re welcome!

Contributing

If you think there’s any way to improve this package, or if you spot a bug don’t be afraid to open PRs, issues or requests of any kind! Any contribution is welcome 💜