Any expression in o42a either constructs a new object, or addresses an existing one.
An expression is one of:
- reference, which addresses some object;
- unary or binary operator;
- object constructor expression;
- array constructor;
- or grouping expression.
A grouping expression is any expression enclosed into parentheses. It can be used e.g. to change the priority of operators:
(a + b) * c ~~ Multiply the sum of `a` and `b` by `c`.
There is a special syntax to avoid the use of parentheses at the very beginning of expression:
Some expression\ another expression
which is the same as
(Some expression) another expression
Such syntax is especially useful with combination of subsequent phrases, in order to distinguish one from another:
"Some string": substring _from \  ~~ "t" ~~ This is the same as following: ("Some string": substring _from ) 
Note that the grouping expression has higher priority than any operator, so it works for its operands, not for the whole operator:
a + b\ c * d ~~ The above expression is the same as: a + (b\ c) * d ~~ or, more precisely: a + ((b _c) * d)