apple/pkl · error · ParseException

Cannot parse ` ` as number.

Error message

Cannot parse `%s` as number.

What it means

While parsing a JSON document, a number token could not be converted to either a Long or a Double. This means the token is syntactically a number per the tokenizer but numerically unrepresentable in Java (typically an out-of-range literal).

Solutions

1. Quote oversized numbers as strings in the JSON source and convert manually if needed
2. Fix the generator producing the JSON to emit numbers within Long/Double range
3. Pre-transform the JSON (e.g. with a script) to normalize extreme numeric literals

Example fix

// before (input.json)
{"id": 123456789012345678901234567890}
// after
{"id": "123456789012345678901234567890"}

function isSafeNumber(n) { return Number.isFinite(n) && Math.abs(n) <= Number.MAX_VALUE && Number.isInteger(n) ? n <= Number.MAX_SAFE_INTEGER || typeof n === 'number' : !Number.isFinite(n); }

const isInRangeNumber = (s) => { const n = Number(s); return Number.isFinite(n); };

try { const v = Json.parse(text); } catch (e) { if (e instanceof ParseException && /Cannot parse .* as number/.test(e.message)) { /* normalize the numeric literal */ } else throw e }

When it happens

Trigger: Parsing JSON (via Pkl's JSON parser used for `fromJson`/import of `.json`) containing a numeric literal too large or too small for Long/Double, e.g. `1e999` or a 20+ digit integer.

Common situations: Importing machine-generated JSON with huge IDs (e.g. 64-bit-plus snowflake IDs serialized as numbers, or `Infinity`-like `1e999` exponents) into Pkl.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• '" + ch + "'
• digit
• ':'
• hexadecimal digit
• name

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/624bff6bccaeff57. Report an issue: GitHub.

Appendix: source

Thrown at pkl-core/src/main/java/org/pkl/core/stdlib/json/ParserNodes.java:107

    @Override
    public void endBoolean(boolean value) {
      this.value = value;
    }

    @Override
    public void endString(String string) {
      value = string;
    }

    @Override
    public void endNumber(String string) {
      try {
        value = Long.valueOf(string);
      } catch (NumberFormatException e) {
        try {
          value = Double.valueOf(string);
        } catch (NumberFormatException e2) {
          throw new ParseException("Cannot parse `" + string + "` as number.", getLocation());
        }
      }
    }

    @Override
    public EconomicMap<Object, ObjectMember> startArray() {
      currPath.push(VmValueConverter.WILDCARD_ELEMENT);
      return EconomicMaps.create();
    }

    @Override
    public void endArray(@Nullable EconomicMap<Object, ObjectMember> members) {
      assert members != null;
      value =
          new VmListing(
              VmUtils.createEmptyMaterializedFrame(),
              BaseModule.getListingClass().getPrototype(),
              members,

View on GitHub (pinned to f3efcbfc9b)