Reference Statements

Statements Reference

This document provides a complete reference for all statement types in ARO.

ARO Statement

The fundamental statement type following the Action-Result-Object pattern.

Syntax

<Action> [article] <result> preposition [article] <object> [modifiers].

Components

Component	Required	Description
Action	Yes	Verb in angle brackets
Article	No	a, an, or the
Result	Yes	Output variable
Preposition	Yes	Relationship word
Object	Yes	Input/target
Modifiers	No	where, with, on, when clauses

Examples

<Extract> the <user-id> from the <request: parameters>.
<Create> a <user> with <user-data>.
<Return> an <OK: status> for the <request>.
<Store> the <order> into the <order-repository>.
<Retrieve> the <user> from the <repository> where id = <user-id>.
<Start> the <http-server> on port 8080.

Publish Statement

Makes a variable globally accessible across feature sets.

Syntax

<Publish> as <alias> <variable>.

Components

Component	Description
alias	Name to publish under
variable	Variable to publish

Example

<Read> the <config> from the <file: "./config.json">.
<Publish> as <app-config> <config>.

Guarded Statement (when)

Conditionally executes a statement based on a condition. If the condition is false, the statement is skipped.

Syntax

<Action> the <result> preposition the <object> when <condition>.

Conditions

Condition	Description
<var> is <value>	Equality
<var> is not <value>	Inequality
<var> is empty	Null/empty check
<var> is not empty	Has value
<var> exists	Value exists
<var> is null	Null check
<var> > <value>	Greater than
<var> < <value>	Less than
<var> >= <value>	Greater or equal
<var> <= <value>	Less or equal
<cond1> and <cond2>	Both true
<cond1> or <cond2>	Either true
not <cond>	Negation

Examples

(* Return not found only when user is empty *)
<Return> a <NotFound: status> for the <missing: user> when <user> is empty.

(* Send notification only when user has email *)
<Send> the <notification> to the <user: email> when <user: email> exists.

(* Log admin access only for admins *)
<Log> <admin-access> to the <audit> when <user: role> = "admin".

(* Early exit on invalid input *)
<Return> a <BadRequest: status> for the <invalid: amount> when <amount> <= 0.

(* Combined conditions *)
<Grant> the <access> for the <user> when <user: active> is true and <user: verified> is true.

Usage Pattern

(PUT /users/{id}: User API) {
    <Extract> the <user-id> from the <request: parameters>.
    <Extract> the <updates> from the <request: body>.

    (* Early exit guards *)
    <Return> a <BadRequest: status> for the <missing: id> when <user-id> is empty.
    <Return> a <BadRequest: status> for the <missing: data> when <updates> is empty.

    (* Continue with valid input *)
    <Retrieve> the <user> from the <repository> where id = <user-id>.
    <Return> a <NotFound: status> for the <missing: user> when <user> is empty.

    <Transform> the <updated-user> from the <user> with <updates>.
    <Store> the <updated-user> into the <repository>.
    <Return> an <OK: status> with <updated-user>.
}

Match Statement

Pattern matching for multiple cases.

Syntax

match <variable> {
    case <value1> {
        (* statements *)
    }
    case <value2> {
        (* statements *)
    }
    otherwise {
        (* fallback statements *)
    }
}

Case with Guard

match <variable> {
    case <value> where <condition> {
        (* statements *)
    }
}

Example

match <status> {
    case "pending" {
        <Log> "Order is pending" to the <console>.
    }
    case "shipped" {
        <Log> "Order has shipped" to the <console>.
        <Emit> an <OrderShipped: event> with <order>.
    }
    case "delivered" {
        <Log> "Order delivered" to the <console>.
        <Emit> an <OrderDelivered: event> with <order>.
    }
    otherwise {
        <Log> "Unknown status" to the <console>.
    }
}

Pattern Matching with Guards

match <user: subscription> {
    case <premium> where <user: credits> > 0 {
        <Grant> the <premium-features> for the <user>.
        <Deduct> the <credit> from the <user: account>.
    }
    case <premium> {
        <Notify> the <user> about the <low-credits>.
        <Grant> the <basic-features> for the <user>.
    }
    case <basic> {
        <Grant> the <basic-features> for the <user>.
    }
    otherwise {
        <Redirect> the <user> to the <subscription-page>.
    }
}

Return Statement

Exits the feature set with a response.

Syntax

<Return> [article] <status> [with <data>] [for <context>].

Status Codes

Status	HTTP Code	Usage
OK	200	Successful request
Created	201	Resource created
Accepted	202	Async operation started
NoContent	204	Success, no body
BadRequest	400	Invalid input
Unauthorized	401	Auth required
Forbidden	403	Access denied
NotFound	404	Not found
Conflict	409	Resource conflict
UnprocessableEntity	422	Validation failed
TooManyRequests	429	Rate limited
InternalError	500	Server error
ServiceUnavailable	503	Service down

Examples

<Return> an <OK: status> with <data>.
<Return> a <Created: status> with <resource>.
<Return> a <NoContent: status> for the <deletion>.
<Return> a <BadRequest: status> with <validation: errors>.
<Return> a <NotFound: status> for the <missing: user>.
<Return> a <Forbidden: status> for the <unauthorized: access>.

Comment

Adds documentation to code.

Syntax

(* comment text *)

Examples

(* This is a single-line comment *)

(*
   This is a
   multi-line comment
*)

(* Comments can be (* nested *) *)

(Process Order: Order Processing) {
    (* Extract order data from request *)
    <Extract> the <order-data> from the <request: body>.

    (* Validate before processing *)
    <Validate> the <order-data> for the <order-schema>.

    (* Store and return *)
    <Store> the <order> into the <repository>.
    <Return> a <Created: status> with <order>.
}

Where Clause

Filters data in retrieval and deletion.

Syntax

... where <field> = <value>
... where <field> = <value> and <field2> = <value2>

Examples

<Retrieve> the <user> from the <repository> where id = <user-id>.
<Retrieve> the <orders> from the <repository> where status = "pending".
<Retrieve> the <users> from the <repository> where role = "admin" and active = true.
<Delete> the <sessions> from the <repository> where userId = <user-id>.

With Clause

Provides additional data or parameters.

Syntax

... with <variable>
... with <object-literal>
... with <string-literal>

Examples

<Create> the <user> with <user-data>.
<Create> the <config> with { debug: true, port: 8080 }.
<Transform> the <updated> from the <user> with <updates>.
<Send> the <message> to the <connection> with "Hello, World!".
<Log> "Application started" to the <console>.

On Clause

Specifies ports for network operations.

Syntax

... on port <number>

Examples

<Start> the <http-server> on port 8080.
<Listen> on port 9000 as <socket-server>.
<Connect> to <host: "localhost"> on port 5432 as <database>.

When Clause

Conditionally executes a statement.

Syntax

<Action> the <result> preposition the <object> when <condition>.

Examples

<Return> a <NotFound: status> for the <user> when <user> is empty.
<Log> "Low stock" to the <console> when <stock> < 10.
<Send> the <alert> to the <admin: email> when <errors> > <threshold>.

Statement Order

Statements execute sequentially from top to bottom:

(Process Request: Handler) {
    (* 1. First *)
    <Extract> the <data> from the <request: body>.

    (* 2. Second *)
    <Validate> the <data> for the <schema>.

    (* 3. Third *)
    <Create> the <result> with <data>.

    (* 4. Fourth *)
    <Store> the <result> into the <repository>.

    (* 5. Fifth - ends execution *)
    <Return> a <Created: status> with <result>.

    (* Never executed - after return *)
    <Log> "This won't run" to the <console>.
}

Statement Termination

All statements end with a period (.):

(* Correct *)
<Extract> the <data> from the <request>.
<Return> an <OK: status> with <data>.

(* Incorrect - missing period *)
<Extract> the <data> from the <request>

Match blocks use braces without periods on closing brace:

match <status> {
    case "active" {
        <Return> an <OK: status>.  (* Period on inner statement *)
    }
}  (* No period on closing brace *)