future

Compatibility annotation for asynchronous posture.

Syntax: @ future

Category#

async

Related#

• futura
• annotation-sugar

Examples#

radix/corpus/annotation-sugar/futura-braced.fab (canonical · annotation)#

Braced canonical @ future unit marker.

@ future { }
fn f() → void {
    return
}

main {
    print "futura-braced"
}

Expected output:

futura-braced

radix/corpus/futura/futura.fab (canonical · annotation)#

Compatibility annotation for asynchronous posture.

# =============================================================================
# future — Compatibility annotation for asynchronous posture
# =============================================================================
#
# What this teaches:
#   • Preferred async posture — write `async` for a finite async function.
#   • Compatibility annotation — `@ future` remains accepted and preserved as
#     the legacy spelling for async posture.
#   • Related keywords: cursor, await_const, await
#
# Common mistakes:
#   • Calling an async function and forgetting to consume the promise with
#     `await_const`, `await_var`, `return_await`, or `await`.
#
# See also: cursor, await_const, await
# =============================================================================

# @ future — compatibility async function annotation
#
# @ future
# fn name(…) → type { … }
#
# GRAMMAR:
#   annotatedFunc :← '@' 'future' funcDecl
#   callablePosture :← 'async'
#
# EXPECTED OUTPUT:
#   none — Rust async runtime whitelist (compile-only in harness)
#
# BACKEND:
#   Rust async runtime not linked in exempla harness (whitelist: future/futura.fab).

@ future { }
fn responde() → int {
    return 42
}

async_main {
    # await_const awaits the promise and binds the resolved value
    await_const int responsum ← responde()
    print responsum
}

Expected output:

42