zq you can define your own dataflow operators and functions. All functions need to be called with parens, even argumentless ones, whether built-in or user-defined.func <id> ( [<param> [, <param> ...]] ) : ( <expr> )
<id> and <param> are identifiers and <expr> is an expression that may refer to parameters but not to runtime state such as this.”op <id> ( [<param> [, <param> ...]] ) : (
<sequence>
)
<id> is the operator identifier, <param> are the [optional] parameters for the operator, and <sequence> is the chain of operators (e.g., operator | ...) where the operator does its work.” And it can refer to this.Though it's more precise to say the body of a user-defined function is an Expression, and the body of a user-defined operator is a Sequence of Dataflow Operators.
User-defined Function Can only call other functions. Cannot refer to this.User-defined Operator Can call operators and functions. Can refer to this.
❯ zq -z \
'op add_ids(): (
over this
| yield {id:count(), ...this}
)
yield [{name:"lorem"},{name:"ipsum"}] | add_ids()'
{id:1(uint64),name:"lorem"}
{id:2(uint64),name:"ipsum"}
add_ids will take an array of records and add an auto-incrementing id integer to each one.zq things going on here, but for now we'll just focus on calling the operator, with parens. A call without, and again this will fall to the search ImpliedOperator:❯ zq -z \
'op add_ids(): (
over this
| yield {id:count(), ...this}
)
yield [{name:"lorem"},{name:"ipsum"}] | add_ids'
❯
add_ids without parens is interpreted by zq as search add_ids and the string “add_ids” can't be found in the array of two records.