Concept Statements

Concept statements define the semantic building blocks of a Trilogy model. Concepts represent business entities and their attributes.

Syntax

Three forms of concept definitions:

# Declaration: define a new concept with a type
concept_declaration: PURPOSE IDENTIFIER data_type concept_nullable_modifier? metadata?

# Property: define a concept as a property of another
concept_property_declaration: UNIQUE? "property" (prop_ident | IDENTIFIER) data_type concept_nullable_modifier? metadata?

# Derivation: define a concept as a calculation
concept_derivation: (PURPOSE | "auto" | "property") (prop_ident | IDENTIFIER) "<-" expr

Purpose Types

• key: Unique identifier for an entity
• property: Attribute of an entity
• metric: Aggregatable measure
• const/constant: Fixed value
• param/parameter: Runtime parameter

Key Declaration

Define a unique identifier:

key customer_id int;
key order_id string;

Property Declaration

Define attributes attached to a key:

key customer_id int;
property customer_id.name string;
property customer_id.email string;
property customer_id.created_at datetime;

Multi-Key Properties

Define properties spanning multiple keys:

key customer_id int;
key product_id int;
property <customer_id, product_id>.purchase_count int;

Nullable Concepts

Mark concepts as nullable with ?:

property customer_id.middle_name string?;

Metric Declaration

Define aggregatable measures:

key order_id int;
metric order_total float;
metric order_quantity int;

Concept Derivation

Define a concept as a calculation:

key order_id int;
property order_id.price float;
property order_id.quantity int;
auto order_id.total <- price * quantity;

Constant Definition

Define fixed values:

const tax_rate <- 0.08;
const company_name <- 'Acme Corp';

Unique Properties

Mark properties as unique:

key customer_id int;
unique property customer_id.email string;

With Metadata

Add metadata for documentation or tooling:

property customer_id.name string metadata(description = 'Customer full name');

Example

# Define customer entity
key customer_id int;
property customer_id.name string;
property customer_id.email string;
property customer_id.signup_date date;
# Define order entity
key order_id int;
property order_id.customer_id int;
property order_id.total float;
property order_id.created_at datetime;
# Derived concept
auto order_id.total_with_tax <- total * 1.08;
# Metric
metric revenue <- sum(order_id.total);