Control flow

Platform spec node

Control flow

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Spec standingStandard

Owner

Piotr Mikstacki pmikstacki@cybernomad.it

Submitter

Piotr Mikstacki pmikstacki@cybernomad.it

Current document

ADRs

No architecture decision records under adr/ for this feature yet. Standard features must publish at least one ADR or keep a ## Decisions summary on the hub.

Articles

• Control flow Conditionals, loops, and structured control transfer. Lowering to HIR/CLIF follows the evaluation order defined here. article Standard Reviewed Thu May 21
• Events Multicast events, subscription lifetime, and thread affinity assumptions. UI stacks build on these primitives. article Standard Reviewed Thu May 21
• Lambdas and closures Capture lists, environment layout, and lifetime of delegates. JIT and AOT must agree on closure calling conventions. article Standard Reviewed Thu May 21

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Completeness

OKarea · 2 SpecSection(s) · 0 H2 heading(s)

Section id	Required	Found
scope	yes	yes
features	yes	yes

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• Area
  Evaluation

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• Domain
  Language meta

  Parent domain hub

• Domain
  Platform specification

  Cross-cutting index

• Domain
  Execution documentation

  Non-normative legacy execution bridge

Normative specification

Scope

Defines statement-level control flow and structured transfer. Expression-level match is in Enums and match.

Statements

Construct	Rule
if (cond) block else block	cond must be bool (non-bool condition diagnostic)
while (cond) block	cond must be bool; body may loop
for id in expr block	expr must be iterable per type rules (v0.1: range and array-like forms as implemented)
return expr?;	Returns from the innermost function; expr must match return type when present
break; / continue;	Must appear inside a loop; otherwise E1401 / E1402
let / typed let	Introduces locals; see Type inference

Evaluation order

• Function arguments must be evaluated left to right before the call.
• Binary operators must evaluate left operand before right for && and || with short-circuit semantics.
• Assignment must evaluate the right-hand side before storing.

Static rules

• Unreachable code after unconditional transfer may warn (W1403).
• HIR lowering must normalize control flow graphs (E1154 if non-normalized).

Dynamic semantics

• if and while execute the taken branch block sequentially.
• break exits the innermost while/for; continue jumps to the next iteration.

Diagnostics

Control band E1401–E1403; bool condition errors in type band. Registry: Diagnostic code registry.

Conformance

L3 semantic tests for break/continue and return paths must pass.

Decisions

• D-LM-CF-001 — No switch statement: Sum-type branching uses match expressions only.
• D-LM-CF-002 — Short-circuit booleans: && and || are mandatory short-circuit operators.
• D-LM-CF-003 — bool conditions only: if/while must not treat non-bool values as truthy (no C-style 0 truthiness).
• D-LM-CF-004 — Structured transfer only: goto is not in the grammar; use break/continue/return.

Platform view

Conditionals, loops, and structured control transfer. Lowering to HIR/CLIF follows the evaluation order defined here.