19. core.assign

core.assign is a core data operator for explicit scoped value binding.

It uses bind entries.

Each bind entry has the form:

bind <source> to=<destination>

core.assign does not evaluate general expressions.

19.1 Source Values

The source side may be:

• a scalar literal
• a string literal, interpreted according to the KAL string model
• a readable KAL reference

The source side must not be:

• a general expression
• a function call
• an operator invocation
• an undeclared reference

19.2 Destinations

The destination side must be an explicit writable destination reference.

Writable destinations include:

• locals.*
• outputs.*
• globals.*, when declared writable
• loop.result.*, inside a core.each do body

inputs.* is not writable.

loop.<as-name> and loop.meta.* are not writable.

19.3 Evaluation and Commit

bind entries are evaluated sequentially in document order.

Bindings are evaluated against a staged write set for that core.assign invocation.

Later bind entries may read staged values produced by earlier bind entries in the same core.assign invocation.

If every binding succeeds, all staged writes commit together atomically.

If any binding fails, all staged writes from that core.assign invocation are discarded.

If the same destination is assigned more than once, the last successful binding in document order determines the committed value.

19.4 Type Validation

If a destination declares a type and the assigned value is statically known to be incompatible, validation fails.

If compatibility depends on a runtime value, assignment fails when evaluated.

19.5 Capture

core.assign does not define standard capture sources in the current draft.

It still participates in normal operator execution semantics, including when guards and language-level execution outcome.

Example:

core.assign "Bind values" {
  bind inputs.name to=locals.name
  bind #true to=locals.enabled
  bind "service-${inputs.name}" to=locals.label
  bind locals.name to=outputs.result
}

Quoted strings, multi-line strings, raw strings, and raw multi-line strings may be used as string literal source values when supported by the KAL string model.

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