seq-compiler 5.4.1

Compiler for the Seq programming language
Documentation 
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# Signal handling for Seq
#
# Provides Unix signal handling with a safe, flag-based API.
# Signals are trapped and set internal flags - user code polls for signals
# at safe points using signal.received? or signal.pending?
#
# Example: Graceful shutdown
#
#   include std:signal
#
#   : main ( -- Int )
#     signal.SIGINT signal.trap
#     signal.SIGTERM signal.trap
#     server-loop
#     0
#   ;
#
#   : server-loop ( -- )
#     signal.SIGINT signal.received?
#     signal.SIGTERM signal.received? or if
#       "Shutting down..." io.write-line
#       return
#     then
#     handle-request
#     server-loop
#   ;

# ============================================================================
# Signal Constants
# ============================================================================
#
# These constants are provided as builtins that return platform-correct values.
# On Linux and macOS, some signal numbers differ (e.g., SIGUSR1 is 10 on Linux
# but 30 on macOS). Using these builtins ensures portability.
#
# Available constants:
#   signal.SIGINT   - Interrupt from keyboard (Ctrl+C)
#   signal.SIGTERM  - Termination signal (graceful shutdown request)
#   signal.SIGHUP   - Hangup detected on controlling terminal
#   signal.SIGPIPE  - Broken pipe (useful to ignore in network servers)
#   signal.SIGUSR1  - User-defined signal 1
#   signal.SIGUSR2  - User-defined signal 2
#   signal.SIGCHLD  - Child process stopped or terminated
#   signal.SIGALRM  - Alarm clock (timer expired)
#   signal.SIGCONT  - Continue if stopped

# ============================================================================
# Convenience Combinators
# ============================================================================

# Check if either SIGINT or SIGTERM was received (common shutdown pattern)
: signal.shutdown-requested? ( -- Bool )
  signal.SIGINT signal.received?
  signal.SIGTERM signal.received? or
;

# Trap common shutdown signals (SIGINT and SIGTERM)
: signal.trap-shutdown ( -- )
  signal.SIGINT signal.trap
  signal.SIGTERM signal.trap
;

# Ignore SIGPIPE (recommended for network servers)
: signal.ignore-sigpipe ( -- )
  signal.SIGPIPE signal.ignore
;