lời_hứa

Promise-like result type associated with async finite functions.

Aliases: promise

Syntax: lời_hứa<T> | lời_hứa<T ⇥ E>

Category#

async

Related#

• async
• tương_lai
• đợi_hằng
• đợi_bỏ

Examples#

radix/corpus/promissum/promissum.fab (canonical · keyword)#

Promise-like result type associated with async finite functions.

# =============================================================================
# lời_hứa — Promise-like result type associated with async finite functions.
# =============================================================================
#
# What this teaches:
#   • Async return type — `lời_hứa<T>` is the return-type wrapper for `async`
#     functions and compatibility `@ tương_lai` functions.
#   • Failable async return type — `lời_hứa<T ⇥ E>` preserves both the
#     resolved value and delayed alternate channel.
#
# Common mistakes:
#   • Creating a `lời_hứa<T>` but never awaiting it with `đợi_hằng`,
#     `đợi_biến`, `đợi_trả`, or `đợi_bỏ` — the promise goes unobserved.
#
# See also: async, tương_lai, đợi_hằng, đợi_bỏ
# =============================================================================

# lời_hứa<T> — async result type (paired with async)
#
# hàm … async → <kiểu_tên>       -- lowers to lời_hứa<<kiểu_tên>>
# hàm … async → <kiểu_tên> ⇥ E   -- lowers to lời_hứa<<kiểu_tên> ⇥ E>
#
# GRAMMAR:
#   futuraDecl :← funcDecl 'async'
#
# EXPECTED OUTPUT:
#   lời_hứa kiểu_tên notus (promissum.expected).

fn compute() async → int {
    return 7
}

main {
    print "promissum typus notus"
}

Expected output:

promissum typus notus