Expressions and operators

Arithmetic/concatenation operators

Operator	Use
`+`	Numeric addition between `Number`s, or concatenation between `char`/`varchar` (depending on the operand types).
`-`	Numeric subtraction.
`*`	Numeric multiplication.
`/`	Numeric division.

&Total = &Price * &Quantity
&Greeting = "Hello, " + &Username

=, <>, <, <=, >, >= — used in Where, If, While.

And/Or combine comparisons (typically in If/While): And binds tighter than Or. Not expr negates a condition.

If &a = 1 And &b = 2 Or &c = 3
    ...
EndIf

Not expr inverts the condition that follows it. It is a reserved word, like And and Or.

Precedence, from lowest to highest: Or, And, Not, comparisons. That is, Not binds looser than a comparison and tighter than And:

// Not &a = 1 And &b = 2  reads as  (Not (&a = 1)) And (&b = 2)
If Not &a = 1 And &b = 2
    ...
EndIf

To negate a compound condition, use parentheses: Not (&a = 1 Or &b = 2).

Not can also be used in @Layout conditions (see @Layout: conditions).

WARP has no boolean type of its own: each operand is validated like any other expression.

In @Source, an expression or statement can span several lines without any special character. The line break is ignored in these cases:

After an operator: + - * /, the comparisons = <> < <= > >=, And, Or, Not, and after the = of an assignment.
Inside parentheses: after (, after each , and before ). This applies to function or builtin calls (DateAdd(…)), Do Proc(...), Call(...), Message(...), Member(...), Export(...), Procedure/Function parameter lists and parenthesized expressions.
And/Or at the start of the next line also continue the condition.

&text = "one" +
    "two"

&d = DateAdd(
    &d,
    1,
    Days
)

If &n > 1
   And &n < 10
    ...
EndIf

Additional rules:

An arithmetic or comparison operator at the start of the next line (for example + "two") is still an error (E00008), because it would be ambiguous.
A line cannot be continued in the middle of an identifier or a text literal.
// comments between continued lines are ignored.
Diagnostic line numbers remain the real ones.

Variable: always with & (&Username).
Table field: without &, only inside a For Each/New over that table (CustCode, Name).
list/matrix element: &Variable[index] / &Variable[row, col] (1-based).
list method: &Variable.Method(...) (Add/Clear/Init/Remove as a statement, Count() as an expression) — see Data types: List.
Json() method of struct, list(struct(...)) and scalar list (list(char), list(number), list(date), list(time), list(timestamp); the result is a JSON array, e.g. ["a","b"] or [1,2])
Statement JsonSplit(&json, &list[, indent]): splits a JSON into lines — see JsonSplit.
Fixed-width records: expression &rec.FixedWidth() and statements &rec.FromFixedWidth(&text), FixedWidthSplit(&records, &lines), FixedWidthParse(&lines, &records) — see Fixed-width records.
struct member: &Variable.Member (read and assignment); with nested structs, by path: &Variable.Cab.Member, &Variable.Cab.List.Add(&row), &Variable.Cab.List[1] — see Data types: Struct.

&variable = FunctionName(expr, ...)