Core DSL fundamentals

The Core DSL uses closed-record contracts. Unknown fields, malformed identifiers, invalid timeout strings, and wrong reference types fail at the constructor call instead of becoming runtime surprises.

Task

mkTask requires:

• name;
• nix_expression_path;
• args.

It defaults outputs, inputs, and secrets to empty arrays and max_attempts to 3. Optional fields include routing_vars, emits, and timeout.

let result = tickr.mkRoutingVar { name = "result", type = "string" } in
let produce = tickr.mkTask {
  name = "produce",
  nix_expression_path = "path:./tasks#produce",
  args = [],
  inputs = [],
  outputs = ["result"],
  routing_vars = [result],
  timeout = "5m",
} in

Pass constructor values as typed references. Do not replace a Task reference with its name string at an edge or gate call site.

Task group

A Task group is a locally complete graph fragment with Tasks and edges:

tickr.mkTaskGroup {
  name = "processing",
  args = [],
  outputs = [],
  tasks = [extract, transform, load],
  edges = [
    tickr.mkEdge { from = extract, to = transform },
    tickr.mkEdge { from = transform, to = load },
  ],
}

The chain combinator removes duplicate ordering declarations for an ungated sequence; see Compose a graph.

Workflow

mkWorkflow defines the authored root. Its fields include:

Field	Meaning
slug	Stable URL-safe workflow name
name	Human-readable identifier
args	Workflow arguments
tasks	Task groups or accepted task entries
outputs	Declared workflow outputs
triggerOn	Optional trigger configuration
captures	Trigger capture declarations
timeout	Optional workflow duration
tags	Workflow tags

Defaults are applied by the release-matched constructor. Prefer omitting optional values to inventing sentinel strings.

Gates

Gates are attached to edges:

• mkSignalGate waits for a named Signal and optional predicate/captures.
• mkTimerGate waits for a duration.
• mkPredicateGate compares a routing variable against a scalar value.

A gated edge must explicitly use kind = "data" or kind = "loop". A plain control edge has no gate and does not use those kinds.

Validate before registration

From a source checkout:

nickel export workflow.ncl --format json -I dsl

From a release archive, point Nickel at the bundled $TICKR_DSL_PATHS. A successful export proves DSL evaluation; registration and build still apply Data-plane validation.