ProgramSchema.ts

// A program consists of a sequence of function calls that are evaluated in order.
export type Program = {
    "@steps": FunctionCall[];
    // Collect parts of the user request that could not translated.
    // Including if NO suitable API provided
    "@cannot_translate"?: string[];
}

// A function call specifies a function name and a list of argument expressions. Arguments may contain
// nested function calls and result references.
export type FunctionCall = {
    // Name of the function
    "@func": string;
    // Arguments for the function, if any
    "@args"?: Expression[];
};

// An expression is a JSON value, a function call, or a reference to the result of a preceding expression.
export type Expression = JsonValue | FunctionCall | ResultReference;

// A JSON value is a string, a number, a boolean, null, an object, or an array. Function calls and result
// references can be nested in objects and arrays.
export type JsonValue = string | number | boolean | null | { [x: string]: Expression } | Expression[];

// A result reference represents the value of an expression from a preceding step.
export type ResultReference = {
    // Index of the previous expression in the "@steps" array
    "@ref": number;
};