Conditional

A condition is a logical (boolean) expression resulting in true or false. Conditions are used in when statements to control flow and in match statements for pattern matching.

Natural-Language Conditions¶

The simplest form describes the condition in natural language, wrapped in prompt(…) so it is clear an AI decides it:

when prompt("the user is authenticated") then {
  // actions when the condition holds
} end

This lets authors express conditions at the appropriate level of abstraction. Evaluating the condition is left to code generation.

The bare-string form is deprecated

when "user is authenticated" then { ??? } end   // deprecated

It still parses, but draws a [deprecated] message. Everywhere else in RIDDL a bare quoted string denotes a literal value, while prompt(…) marks something an AI decides — so a natural-language condition should say which of the two it is rather than borrowing the literal's spelling.

Identifier Conditions¶

Conditions can reference identifiers defined with let:

let isValid = "order.items.count > 0"
when isValid then {
  // actions when valid
} end

Identifiers can be negated:

when !isValid then {
  error "Order must have at least one item"
} end

Numeric Expressions¶

Numeric expressions involve comparisons and arithmetic:

Comparison operators: >, <, >=, <=, ==, !=
Arithmetic operators: +, -, *, /

when "order.total > 100" then {
  // apply discount
} end

Note: In RIDDL, these expressions are typically written as strings that describe the intended logic. The actual parsing and evaluation happens during code generation.

Boolean Expressions¶

Boolean expressions combine conditions using logical operators:

AND: Both conditions must be true
OR: Either condition must be true
NOT: Negates a condition

when "user.isVerified AND order.total > 0" then {
  // process order
} end

Match Expressions¶

The match statement provides pattern matching:

match "orderStatus" {
  case "pending" {
    // handle pending
  }
  case "processing" {
    // handle processing
  }
  case "shipped" {
    // handle shipped
  }
  default {
    // handle unknown status
  }
}

Occurs In¶

Statements - specifically when and match statements

Contains¶

Conditions are leaf elements containing:

String literals describing the condition
Identifier references
Logical operators combining sub-conditions