error not-overloadable

What it means#

Overloading with op is possible for arithmetic, bitwise, comparison (through <=>), [], (), as and compound assignment operators. These cannot be overloaded: && || ?? ?. ? ! is = -> ?-> ~> !> |> =>, . and .. (§5.3).

Example#

data Flag { on: bool }

impl Flag {
  static op &&(a: Flag, b: Flag) -> Flag => Flag{ on: a.on }      // <- not-overloadable
}

not-overloadable

How to fix#

data Flag { on: bool }

impl Flag {
  fn and(other: Flag) -> Flag => Flag{ on: on }
}

Use an ordinary method, or declare a new operator with the operator keyword and a free symbol.

See also#

• operator-decl