Overview of Call Arguments

Quxlang calls use named arguments for ordinary APIs and explicit positional groups when order is an intentional part of the interface.

Named arguments

A named argument begins with its parameter's public name:

::ceil_div FUNCTION(@numerator:n I32, @denominator:d I32): I32
{
  RETURN (n + d - 1) / d;
}

VAR result I32 := ceil_div(@numerator 9, @denominator 2);

The declaration can give the body a shorter local name after :. Calls still use @numerator and @denominator. Named arguments can be reordered without changing which parameters they initialize:

VAR same_result I32 := ceil_div(@denominator 2, @numerator 9);

One bare argument

A function whose single parameter is named @ARG can be called with one bare expression:

::twice FUNCTION(@ARG I32): I32
{
  RETURN ARG * 2;
}

ASSERT(twice(6) == 12);

For multiple arguments, write explicit names or positional groups.

Template argument lists use the same grammar, with one deliberate convention: a single bare template argument binds @T, while a single bare function argument binds @ARG.

Positional groups

Positional parameters begin with % in the declaration and are passed inside % [...]:

::sum_pair FUNCTION(%left I32, %right I32): I32
{
  RETURN left + right;
}

ASSERT(sum_pair(% [4, 5]) == 9);

Named arguments and positional groups can be interleaved. Their expressions are evaluated in the order written:

combine(
  % [first_expression()],
  @mode selected_mode,
  % [second_expression(), third_expression()]
);

Constructor calls use :(...) for the same mixed argument grammar and :[...] for a positional-only sequence.

Template positional arguments use the same % [...] spelling:

VAR value intentionally_positional#(% [I32, F64]);

Composite arguments

APPLY arguments TO target uses a composite as a set of named arguments. It evaluates arguments first and target second. Functions can capture unmatched named arguments with a final @KWARGS ... parameter.

Reference

See the Call Arguments Reference for mapping errors, defaults, constructor forms, and overload interaction.