Wrong number of arguments

Meaning

No callable candidate accepts the number of arguments supplied.

An overload is applicable only when both its arity and exact parameter types match. The twice call below has no two-argument candidate.

print and println are the exception, and not by having a two-argument overload: several values in one call is a rewrite in the compiler, so println(1, 2) is a program rather than this error.

Why it happens

The caller may be using an outdated signature, combining two output calls into one, omitting a required value, or assuming default/variadic arguments from another language.

Invalid code

import std.io

fn twice(value: Int) -> Int {
    return value + value
}

fn main() -> Int {
    twice(1, 2)
    return 0
}

Correct code

import std.io

fn twice(value: Int) -> Int {
    return value + value
}

fn main() -> Int {
    println(twice(1))
    return 0
}

Common fixes

Add or remove arguments, check the signature, or call the intended overload. Prismio has no default or variadic arguments in 0.1.

After the count matches, the compiler may report exact type differences. Fix those separately rather than adding casts while the signature is still wrong. For output, print and println do take several values — see Console I/O — but that is a compiler rewrite over the one-value overloads, not a variadic formatting API, and it applies to those four names only.