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JSX API — This page documents the JSX-based API. For alternative approaches, see TOON (declarative) or the Effect builder (TypeScript).

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Import

import { MergeQueue } from "smithers";

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Props

PropTypeDefaultDescription
idstringauto-generatedOptional stable id for the queue group.
maxConcurrencynumber1Maximum number of child tasks within the queue that may run simultaneously.
skipIfbooleanfalseSkip the entire queue subtree when true.
childrenReactNode—Child tasks/control-flow nodes.

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Examples

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Default single-lane

<MergeQueue>
  <Task id="lint" output={outputs.outputC}>{{ value: 1 }}</Task>
  <Task id="build" output={outputs.outputC}>{{ value: 2 }}</Task>
  <Task id="test" output={outputs.outputC}>{{ value: 3 }}</Task>
</MergeQueue>

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Custom concurrency

<MergeQueue maxConcurrency={2}>
  {items.map((it, i) => (
    <Task key={i} id={`t${i}`} output={outputs.outputC}>{{ value: i }}</Task>
  ))}
</MergeQueue>

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Nesting with Parallel

<Parallel maxConcurrency={3}>
  <MergeQueue>
    {items.map((it, i) => (
      <Task key={i} id={`q${i}`} output={outputs.outputC}>{{ value: i }}</Task>
    ))}
  </MergeQueue>
  <Task id="other" output={outputs.outputC}>{{ value: 99 }}</Task>
</Parallel>
  • The inner <MergeQueue> constrains its children to 1-at-a-time.
  • The outer <Parallel> may still run other, unrelated siblings (outside the queue) concurrently up to its limit.

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Rendering

Internally, <MergeQueue> renders as a <smithers:merge-queue> host element (or null when skipped). Each child task inside the queue receives parallelGroupId and parallelMaxConcurrency in its task descriptor. The engine enforces that no more than parallelMaxConcurrency tasks sharing the same parallelGroupId run at once.

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Notes

  • Defaults to a single-lane queue (maxConcurrency = 1).
  • Designed as a convenient merge-queue primitive for sequentializing task application (e.g., applying patches one-at-a-time).
  • Nesting with <Parallel> is supported; the innermost group determines the effective cap for its descendants.
  • Tasks outside the queue are unaffected by the queue’s limit.