YAML-to-JSON conversion drops .0 from whole-number floats (50.0 → 50)

[dustinblack]

Description

When converting YAML to JSON with -o json, whole-number float values like 50.0 are output as integers (50). This loses type information that YAML explicitly preserves via the !!float tag.

Reproduction

# test.yaml
percentiles:
  - 50.0
  - 95.0
  - 99.0
  - 99.9

$ yq -o json '.' test.yaml

Expected output

{
  "percentiles": [
    50.0,
    95.0,
    99.0,
    99.9
  ]
}

Actual output

{
  "percentiles": [
    50,
    95,
    99,
    99.9
  ]
}

Impact

This creates mixed-type lists in JSON (3 integers + 1 float) from what was a uniform float list in YAML. Downstream consumers that enforce uniform list types reject the output. For example, the Horreum performance data store rejects payloads containing mixed int/float lists.

In our case, YAML output from the Arcaflow engine correctly contains 50.0, but post-processing with yq -o json truncates these to 50, requiring a Python workaround to re-coerce them back to floats.

Environment

• yq version: v4.44.6 and v4.45.4 (tested both, same behavior)
• OS: Linux (aarch64)

Notes

While JSON's number type doesn't formally distinguish integers from floats, most JSON encoders (including Go's encoding/json, Python's json, and jq) do preserve 50.0 as a float in output. YAML explicitly tags these values as !!float, so the type information is available to yq during conversion.