hakorune/docs/guides/dev-local-alias.md

Dev Sugar: @name = expr as local declaration

Status: dev-only, pre-expand sugar (no spec change)

Goal

• Speed up local declarations during development without impacting readability in shared code.

Syntax (dev sugar)

• Line-head only:
  • @name = expr → local name = expr
  • @name: Type = expr → local name: Type = expr

Rules

• Valid only at line start (leading spaces allowed). Inside expressions it is ignored.
• Declaration-only: not allowed for reassignments; use name = expr for assignments.
• Semantics are identical to local (scope/cleanup unchanged). Zero runtime cost.

Enablement

• Use the provided pre-expander script for dev: tools/dev/at_local_preexpand.sh.
• Example:
  • tools/dev/at_local_preexpand.sh apps/tests/dev_sugar/at_local_basic.nyash > /tmp/out.nyash
  • NYASH_VM_USE_PY=1 ./target/release/nyash --backend vm /tmp/out.nyash

Style

• Shared/committed code: prefer explicit local (nyfmt may normalize @ to local).
• Dev/repl/prototype: @ is acceptable to reduce noise.

Notes

• This is a text pre-expansion; it does not change the parser or MIR.
• The pattern is conservative to avoid collisions with comments and inline usages.