5.3. Primary Expressions#

Syntax#

(* Introduced in 0.5.3 *)
TypeExpression = (* type_keyword: *) TYPE_KEYWORD
                 (* open_paren: *) OPEN_PAREN
                 (* type_name: *) TypeName
                 (* close_paren: *) CLOSE_PAREN;

NewExpression = (* new_keyword: *) NEW_KEYWORD
                (* type_name: *) TypeName;

TupleExpression = (* open_paren: *) OPEN_PAREN
                  (* items: *) TupleValues
                  (* close_paren: *) CLOSE_PAREN;

TupleValues = (* item: *) TupleValue ((* separator: *) COMMA (* item: *) TupleValue)*;

TupleValue = (* expression: *) Expression?;

ArrayExpression = (* open_bracket: *) OPEN_BRACKET
                  (* items: *) ArrayValues
                  (* close_bracket: *) CLOSE_BRACKET;

ArrayValues = (* item: *) Expression ((* separator: *) COMMA (* item: *) Expression)*;

Array Literals#

An array literal is a comma-separated list of one or more expressions, enclosed in square brackets ([...]). For example [1, a, f(3)]. It is always a statically-sized memory array whose length is the number of expressions.

contract MyContract {
    function someFunction() public pure {
        otherFunction([uint(1), 2, 3]);
    }
}

Array Slices#

Array slices are a view on a contiguous portion of an array. They are written as x[start:end], where start and end are expressions resulting in a uint256 type (or implicitly convertible to it). The first element of the slice is x[start] and the last element is x[end - 1].

Both start and end are optional: start defaults to 0 and end defaults to the length of the array.