Defaults and named arguments in Kotlin

Signatures carry the defaults, so call sites stay short.

// Default values live in the signature; = makes an expression body.
fun paceMinPerKm(minutes: Int, km: Double = 10.0) = minutes / km

fun campNote(site: String, tents: Int = 1, fires: Boolean = false): String {
    val fireNote = if (fires) "fire ring in use" else "no fires"
    return "$site: $tents tents, $fireNote"
}

fun main() {
    println(paceMinPerKm(85))
    // Named arguments skip past the defaults you keep.
    println(campNote("Boulder Flats", fires = true))
}

How it works

1. km: Double = 10.0 is a default; = after the signature is an expression body.
2. campNote mixes required and defaulted parameters in one signature.
3. campNote("Boulder Flats", fires = true) names an argument to skip the rest.

Keywords and builtins used here

• Boolean
• Double
• Int
• String
• campNote
• else
• fun
• if
• main
• paceMinPerKm
• return
• val

The run, in numbers

Lines

13

Characters to type

457

Tokens

95

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 81 seconds.

Type this snippet

Step 1 of 3 in Functions, step 7 of 27 in Language basics.

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Defaults and named arguments in other languages

• SQL