ZqFunctionsNeedParens

from LearningZq

examples use zq version 1.16.0 and jq version 1.7

Knowing the difference between an operator and a function in Zed can be confusing to me because there's not a hard distinction like that in jq (not to mention “operators” in jq docs refer to things like + and -, and zq “dataflow operators” are things like over, yield, and put).

In addition, functions with zq always need to be called with parentheses, even if it has no arguments (like the now function). But in jq, argumentless functions receive their input via the pipe | operator and don't have parens, like Dataflow Operators in zq.

❯ echo "[1,2,3]" | jq 'length'
3
❯ echo "[1,2,3]" | jq 'length()'
jq: error: syntax error, unexpected ')' ... at <top-level>, line 1:
length()
jq: 1 compile error

While I don't have any advice on how to “just know” when a built-in zq “thing” is a dataflow operator vs. a function (I generally have to look all those things up anyway with either tool) the rule to keep in mind in zq is if it's a function, it's gotta have parens.

❯ echo '{a:null}' | zq 'now() | {a:this}' -
{a:2024-07-12T14:25:24.70848Z}

If it doesn't have parens, then, in many cases it won't even error out, it'll fall back to the search implied operator. (see ZqImpliedOperator).

❯ echo '{a:null}' | zq 'now | {a:this}' -
❯

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