v1.2.0

[minirang]

Description

• Performance: replaced the exception-based return/stop control-flow implementation
  with an explicit ExecOutcome value threaded through execStatement/execBlock/execIf/
  execLoop (engine/interpreter/Signals.h). C++ exceptions are reserved for genuine
  CuffError conditions again. Measured effect: a fib(27) recursion benchmark (~635k
  function calls) went from 2.75s to 0.26s (~10.7x). This also fixed two real bugs the
  exception-based version had: stop used inside a function with no loop of its own used to
  leak through the function-call boundary and terminate whatever loop was active in the
  caller; and return/stop used at the top level (outside any function/loop) used to
  crash the whole process with an uncaught exception. Both are now clean, catchable
  CuffRuntimeErrors (StopOutsideLoop, ReturnOutsideFunction).

• Async: calling an async function without await no longer runs it immediately —
  it's queued and runs once the entire top-level script's synchronous code has finished,
  in the order it was queued (FIFO). await is unchanged (still runs immediately and
  returns the value). This is cooperative, single-threaded deferral — not real concurrency —
  chosen for safety (the interpreter's shared state isn't thread-safe). See
  docs/IMPLEMENTATION_NOTES.md section 1 and examples/10_async_ordering.cuff.

• DLC libraries: added DLC:list (sort, reverse, join, unique — all
  non-mutating) and DLC:convert (to_number, to_str, to_boolean).

• Fixed a parser bug uncovered while adding DLC:list: use DLC:<name>/use <name> from ... only accepted an IDENTIFIER token for the name, so any name colliding with a
  reserved word (like list) failed to parse at all. ImportParser now accepts any
  word-shaped token (identifier or keyword) as a name.

• Minor interpreter micro-optimizations: Environment pre-sizes its variable table for a
  function call's known parameter count, and arguments are moved rather than copied into
  parameter bindings.

• Added examples/10_async_ordering.cuff and expanded examples/08_dlc_libraries.cuff to
  cover the new libraries.

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This discussion was created from the release v1.2.0.