`jaq` vs `jq` differ with `--slurp`

[polarathene]

With two separate JSON files, jq and jaq presently differ in output. It seems jaq is not merging the inputs into a single array as is expected when using --slurp?

Verified to occur on both current stable and preview releases:

• https://github.com/01mf02/jaq/releases/tag/v2.3.0
• https://github.com/01mf02/jaq/releases/tag/v3.0.0-alpha

$ jaq --version
jaq 3.0.0-alpha

$ jq --version
jq-1.7.1

---

The intent is to merge/operate on multiple file inputs as if they were a single array, as jq output shows. jaq output seem to have been processed individually, similar to yq? (which doesn't support an equivalent --slurp flag)

arg-1.json:

[{ "arg": "hello" }]

arg-2.json:

[{ "arg": "world" }]

Reproduction of problem:

$ jq -sr 'map("--arg " + .[].arg) | join(" ")' arg-*.json
--arg hello --arg world

$ jaq -sr 'map("--arg " + .[].arg) | join(" ")' arg-*.json
--arg hello
--arg world

We can see the difference here (no improvement if I remove the wrapping array in the individual files):

$ jq --slurp '.' arg-*.json
[
  [
    {
      "arg": "hello"
    }
  ],
  [
    {
      "arg": "world"
    }
  ]
]

$ jaq --slurp '.' arg-*.json
[
  [
    {
      "arg": "hello"
    }
  ]
]
[
  [
    {
      "arg": "world"
    }
  ]
]

Related help text for -s / --slurp suggests that jaq should also be showing a merged array?:

$ jaq --help | grep slurp
  -s, --slurp               Read (slurp) all input values into one array

$ jq --help | grep slurp
  -s, --slurp               read all inputs into an array and use it as the single input value;

Collapsed for brevity

These two are equivalent though (join is ineffective as they're not treated as within the same array):

$ jq -sr '.[] | map("--arg " + .arg) | join(" ")' arg-*.json
--arg hello
--arg world

$ jaq -sr '.[] | map("--arg " + .arg) | join(" ")' arg-*.json
--arg hello
--arg world

As is this:

$ jq -r 'map("--arg " + .arg) | join(" ")' arg-*.json
--arg hello
--arg world

$ jq -r 'map("--arg " + .arg) | join(" ")' arg-*.json
--arg hello
--arg world

[01mf02]

This is intentional and documented; see https://gedenkt.at/jaq/manual/#--slurp.

[polarathene]

Ah okay that works great thanks!:

$ jaq -sr 'map("--arg " + .arg) | join(" ")' <(cat arg-*.json)
--arg hello --arg world

---

Do you think the help message could be revised? Maybe something like:

Read (slurp) all input values into one array (per input stream)

I don't know if "input stream" is the correct phrasing (maybe "source inputs"), but perhaps there are other ways beyond just multiple files alone 🤷‍♂️ Bit muddy with "input values" however.

[01mf02]

@polarathene, thanks for your suggestion! I have updated the docs to say "(per file)".

[polarathene]

Thanks! ❤️