Conditional expressions

CEL uses if expressions to select a branch value. For the exact grammar, see the Reference Manual.

Concept

An if expression selects one branch value. It is an ordinary expression and can appear anywhere an expression is expected.

Syntax

if_expression = "if" expression "{" expression "}"
              [ "else" ( "{" expression "}" | if_expression ) ] .

Worked examples

if ready { 1 } else { 0 }
if score > 90 { "high" } else if score > 75 { "mid" } else { "low" }

Exact rules

• CEL supports the branch forms if, if ... else, and if ... else if ... chains.
• The condition reserves the following body brace. Parenthesize a record constructor in the condition, such as if (Point { x: 0.0 }).x == 0.0 { 1 } else { 2 }. Branch bodies are ordinary expressions.
• Omitting the final else supplies an implicit () branch, so the remaining branches must still be type-compatible with unit.
• The braces belong to if syntax. CEL does not use free-standing block expressions.

Edge cases

• if flag { () } else if other { () } is valid without a final else because the omitted branch is also ().