apple/pkl · error · VmException

inlineNotSupportedHere

inlineNotSupportedHere

Error message

inlineNotSupportedHere

What it means

While rendering XML, a `Typed` object recognized as an inline XML value (satisfies `isXmlInline`) appeared where the renderer cannot emit it. The renderer throws instead of producing malformed output.

Source

Thrown at pkl-core/src/main/java/org/pkl/core/stdlib/xml/RendererNodes.java:193

    @Override
    public void visitIntSeq(VmIntSeq value) {
      cannotRenderTypeAddConverter(value);
    }

    @Override
    protected void startDynamic(VmDynamic value) {
      if (isXmlElement(value)) {
        throw new VmExceptionBuilder()
            .evalError("elementNotSupportedHere")
            .withProgramValue("Value", value)
            .build();
      }
    }

    @Override
    public void startTyped(VmTyped value) {
      if (isXmlInline(value)) {
        throw new VmExceptionBuilder()
            .evalError("inlineNotSupportedHere")
            .withProgramValue("Value", value)
            .build();
      }
    }

    // No-op for XML
    @Override
    protected void startListing(VmListing value) {}

    // No-op for XML
    @Override
    protected void startMapping(VmMapping value) {}

    // No-op for XML
    @Override
    protected void startList(VmList value) {}

View on GitHub (pinned to f3efcbfc9b)

Solutions

1. Place the inline value where the renderer accepts it (inside element content)
2. Convert the inline node to a regular XmlElement-shaped Dynamic object
3. Render the value to a string first if only text is allowed at that position
4. Verify you are using the intended XML rendering entry point from pkl-xml

Example fix

// before
attr = xmlInline("...")   // inline value in attribute slot
// after
content { xmlInline("...") }

function isInline(v: Any): Boolean = v is Typed && v.hasClassProperty("xmlInline") // adapt to pkl-xml API

function renderableHere(v: Any): Boolean = !(v is Typed) || !isXmlInlineValue(v)

When it happens

Trigger: An Xml-inline class instance (from pkl-xml's `XmlInline` machinery) is visited in an unsupported position, e.g. as an attribute value or top-level in a mode that doesn't accept inline nodes.

Common situations: Mixing pkl-xml inline/element abstractions with the generic XML renderer output path; nesting inline nodes where only elements or text are allowed.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• elementNotSupportedHere
• Maps containing non-String keys cannot be rendered as JSON.
• Values of type `TypeAlias` cannot be rendered as Properties.
• Values of type `Regex` cannot be rendered as Properties. Val
• The top-level value of a YAML stream must have type `Collect

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/19579fd44cc7f0db. Report an issue: GitHub.