Tuples in

About Tuples

A tuple is an ordered container of values. Like all Gleam data types tuples are immutable. Each element of a tuple can be of a different type -- they can even be other tuples.

Tuples are defined as comma-separated values between #( and ): #(1, 2.0, "Three").

#("one", 2)      // Tuple pair (2 values)
#("one", 2, 3.0) // Tuple triplet (3 values)

Tuples with the same length and the same types (in the same order) can be compared for equality.

#(1, 2) == #(1, 2) // Same length, same types, same values, same order
// -> True

#(1, 2) == #(2, 1) // Same length, same types, same values, different order
// -> False

#(1, 2) == #(1, "2") // Same length, different types
// Compile error!

#(1, 2) == #(1, 2, 3) // Different length
// Compile error!

There are three ways in which you can get the contained values out of a tuple:

• Indexing.
• Pattern matching with let.
• Pattern matching with case.

let person = #("Jordan", 52)

// Option 1: Indexing
person.0 // -> "Jordan"
person.1 // -> 52

// Option 2: let
let #(name2, length2) = person
// -> name2 = "Jordan"
// -> length2 = 52

// Option 3: case
case person {
  #(name3, length3) -> {
    name3   // -> "Jordan"
    length3 // -> 52
  }
}

Tuples indexing can be used in case expression guards.

pub fn is_18(person) {
  case person {
    _ if person.1 >= 18 -> True
    _ -> False
  }
}