_{Official ZPE/YASS documentation}Expression query

Overview

ZPEExpressionQuery is the lazy result type produced by a ZEQL expression. It cannot be constructed directly with new.

Creating a query

Queries use the from, in, where and select keywords.

$doubled = from $number in [1, 2, 3]
  select $number * 2

Reference methods

to_list() ⇒ list

Enumerates the query into a new mutable list.

length() ⇒ number

Enumerates and counts the values without retaining a second result list.

first() ⇒ mixed

Returns the first result, or undefined if the query is empty.

to_string() ⇒ string

Enumerates the query and returns its list representation as a string.

Lazy evaluation

Expression queries are lazy. Declaring a query does not immediately enumerate its source or calculate every result. Evaluation begins when a method such as to_list(), length(), first() or to_string() is called.

Use first() when only one result is required, since it avoids processing the rest of the query.

Example

$adults = from $person in $people
  where $person->age >= 18
  select $person->name

print($adults->first())

Its implementation was made available in ZPE 1.14.9 (Spurriergate, September 2026).