apple/pkl · error

cannotParseStringAs

cannotParseStringAs

Error message

cannotParseStringAs

What it means

Thrown by String.toInt() when the string cannot be parsed as an integer. Pkl uses Java's integer parsing (after removing underscores), so any non-integer text — including floats, hex without prefix support, or surrounding whitespace — raises this error with the offending string attached.

Solutions

1. Trim and validate the string contains only an optional sign and digits before calling toInt
2. Use toFloat() first if the value may be decimal, then convert
3. Provide a default: `s.toIntOrNull() ?? default` if available in your Pkl version
4. Reject or sanitize commas/separators before parsing

Example fix

// before
val n = userInput.toInt()
// after
val n = userInput.trim().replace(",", "").toIntOrNull() ?? 0

function isIntString(s: String): Boolean = s.trim().isRegexMatch(/^[+-]?\d+$/, _)

When it happens

Trigger: Calling `"abc".toInt()`, `"3.14".toInt()`, `" 42 ".toInt()` (whitespace not trimmed), or an empty string; also integers out of the 64-bit Long range.

Common situations: Reading values from config files, environment variables, or user input assumed numeric; decimals coming from JSON/YAML strings; localized numbers with separators.

Related errors

• adhocEvalError
• Cannot convert pkl.base#String
• cannotParseCertFile
• charIndexOutOfRange
• charIndexOutOfRange

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/b1a3a9d1807b78f7. Report an issue: GitHub.

Appendix: source

Thrown at pkl-core/src/main/java/org/pkl/core/stdlib/base/StringNodes.java:888

      // ensure no trailing garbage
      if (lexer.next() != Token.EOF) {
        throw new NumberFormatException();
      }

      return parsed;
    } catch (ParserError ignored) {
      throw new NumberFormatException();
    }
  }

  public abstract static class toInt extends ExternalMethod0Node {
    @TruffleBoundary
    @Specialization
    protected long eval(String self) {
      try {
        return toInt(self);
      } catch (NumberFormatException e) {
        throw exceptionBuilder()
            .evalError("cannotParseStringAs", "Int")
            .withProgramValue("String", self)
            .build();
      }
    }
  }

  public abstract static class toIntOrNull extends ExternalMethod0Node {
    @TruffleBoundary
    @Specialization
    protected Object eval(String self) {
      try {
        return toInt(self);
      } catch (NumberFormatException e) {
        return VmNull.withoutDefault();
      }
    }
  }

View on GitHub (pinned to f3efcbfc9b)