package lwt

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Promises and event-driven I/O

Install 

dune-project
 Dependency

github.com Edit opam file Versions (30)

Authors

  1. J
    Jérôme Vouillon
  2. J
    Jérémie Dimino

Maintainers

  1. R
    Raphaël Proust <code@bnwr.net>
  2. Anton Bachin

Sources

6.0.0-beta01.tar.gz
md5=6bb978c590433a218a53722b985a01d4
sha512=529c8c920716cf204efd60a2bad3f817eed6eed120a8e8a8dae763ab7f4c45799a74004d0d0a2b8ec08f37c81b77f1a4813426a25f256b254dfa846c86debe44

Description

A promise is a value that may become determined in the future.

Lwt provides typed, composable promises. Promises that are resolved by I/O are resolved by Lwt in parallel.

Meanwhile, OCaml code, including code creating and waiting on promises, runs in a single thread by default. This reduces the need for locks or other synchronization primitives. Code can be run in parallel on an opt-in basis.

Published: 05 Feb 2026

Dependencies (5)

  1. ocplib-endian
  2. dune-configurator
  3. cppo build & >= "1.1"
  4. ocaml >= "4.14"
  5. dune >= "3.15"

Dev Dependencies (2)

  1. odoc with-doc & >= "2.3"
  2. ocamlfind with-dev-setup & >= "1.7.3-1"

  1. 0install >= "2.15.1"
  2. aches-lwt
  3. activitypub
  4. albatross
  5. alcotest-lwt
  6. alcotest-mirage
  7. ambient-context-lwt
  8. amqp-client >= "1.1.0"
  9. amqp-client-lwt
  10. angstrom-lwt-unix >= "0.11.0"
  11. anthill
  12. anycache-lwt
  13. archi-lwt
  14. arp
  15. awa-mirage
  16. aws-lwt
  17. aws-s3-lwt < "4.4.0" | >= "4.8.1"
  18. awsm-lwt
  19. azure-cosmos-db
  20. balancer
  21. bastet_lwt
  22. bistro
  23. brisk-reconciler
  24. brozip
  25. builder
  26. builder-web
  27. bun >= "0.3.3"
  28. cachet-lwt
  29. calculon
  30. caldav
  31. camltc
  32. canary
  33. capnp-rpc-lwt < "2.0"
  34. capnp-rpc-unix < "2.1"
  35. caqti-mirage
  36. carton < "1.0.0"
  37. carton-git
  38. carton-lwt
  39. catala-format >= "0.2.0"
  40. cf-lwt
  41. chamelon
  42. chamelon-unix
  43. chamo
  44. charrua-client
  45. charrua-unix
  46. chess_com_api
  47. clz
  48. cmdtui-lambda-term
  49. coap
  50. coap-server-lwt
  51. cohttp-curl-lwt
  52. cohttp-lwt
  53. cohttp-lwt-jsoo
  54. cohttp-lwt-unix
  55. cohttp-mirage
  56. cohttp-server-lwt-unix
  57. comby
  58. comby-semantic
  59. conan-lwt
  60. conduit-lwt
  61. conduit-lwt-unix
  62. cowabloga
  63. crunch
  64. cstruct-lwt
  65. csv-lwt
  66. ctypes >= "0.15.0" & < "0.21.1"
  67. ctypes-foreign >= "0.21.1"
  68. current
  69. current-albatross-deployer
  70. current_docker
  71. current_examples
  72. current_git
  73. current_github
  74. current_gitlab
  75. current_ocluster
  76. current_rpc
  77. current_slack
  78. current_web
  79. DkSDKFFIOCaml_Std
  80. dap
  81. data-encoding < "0.1.1"
  82. devkit >= "1.2"
  83. distributed-lwt
  84. dkim-bin < "0.8.0"
  85. dkim-lwt-unix
  86. dkim-mirage
  87. dlm
  88. dmarc
  89. dns-certify
  90. dns-cli
  91. dns-client < "7.0.3"
  92. dns-client-lwt
  93. dns-client-mirage
  94. dns-forward
  95. dns-forward-lwt-unix
  96. dns-lwt
  97. dns-mirage
  98. dns-resolver
  99. dns-server
  100. dns-stub
  101. dnssd
  102. docker_hub
  103. docteur >= "0.0.2"
  104. docteur-solo5
  105. docteur-unix >= "0.0.5"
  106. doi2bib
  107. dream
  108. dream-httpaf
  109. dream-pure
  110. dream-serve
  111. dropbox
  112. dune >= "3.17.2"
  113. dune-rpc-lwt
  114. earlybird
  115. elasticsearch-cli
  116. emoji = "2.0.0"
  117. equinoxe
  118. ethernet
  119. ez_api >= "1.2.0"
  120. ezcurl-lwt
  121. ezjs_min < "0.2"
  122. ezjsonm-lwt
  123. ezresto
  124. ezresto-directory >= "0.5"
  125. faraday-lwt
  126. faraday-lwt-unix
  127. fat-filesystem
  128. fiber-lwt
  129. fsevents-lwt
  130. fswatch_lwt
  131. gdbprofiler
  132. git
  133. git-cohttp
  134. git-cohttp-unix
  135. git-kv >= "0.2.0"
  136. git-mirage
  137. git-paf
  138. git-unix >= "3.2.0"
  139. github
  140. github-hooks
  141. github-unix >= "4.4.0"
  142. gitlab-unix
  143. gitlab_pipeline_notifier
  144. gluten-lwt
  145. gluten-lwt-unix < "0.4.0"
  146. gluten-mirage < "0.4.0"
  147. graphql-lwt
  148. gremlin
  149. grpc-lwt
  150. guardian
  151. gufo
  152. h1
  153. h1-lwt-unix
  154. h2-lwt
  155. h2-lwt-unix < "0.10.0"
  156. h2-mirage
  157. happy-eyeballs-lwt
  158. happy-eyeballs-mirage
  159. hidapi-lwt
  160. hiredis >= "0.6"
  161. hl_yaml
  162. hockmd
  163. http-lwt-client
  164. http-mirage-client
  165. http-multipart-formdata >= "2.0.0" & < "3.0.0"
  166. httpaf-lwt-unix
  167. httpun-lwt
  168. httpun-mirage
  169. httpun-ws-lwt
  170. hvsock
  171. i3ipc
  172. influxdb-lwt
  173. inotify >= "2.4"
  174. inquire < "0.3.0"
  175. interface-prime-lwt
  176. ip2location
  177. ip2locationio
  178. ip2whois
  179. ipv6-multicast-lwt
  180. irc-client-lwt
  181. irc-client-lwt-ssl
  182. irc-client-tls
  183. irmin
  184. irmin-bench
  185. irmin-chunk
  186. irmin-cli
  187. irmin-client
  188. irmin-containers
  189. irmin-fs
  190. irmin-git
  191. irmin-graphql
  192. irmin-http
  193. irmin-indexeddb
  194. irmin-layers
  195. irmin-mirage-git
  196. irmin-mirage-graphql
  197. irmin-pack
  198. irmin-server
  199. irmin-test
  200. irmin-unix
  201. irmin-watcher
  202. joolog
  203. jose < "0.9.0"
  204. js_of_ocaml-lwt >= "3.5.0"
  205. jsoo_broadcastchannel
  206. jsoo_storage
  207. jupyter
  208. jupyter-kernel
  209. kafka < "0.5"
  210. kafka_lwt
  211. kappa-library
  212. ke >= "0.5"
  213. kinetic-client
  214. kubecaml
  215. lambda-runtime
  216. lambda-term >= "3.3.3"
  217. lambda_streams_lwt
  218. launchd
  219. ldp
  220. learn-ocaml
  221. learn-ocaml-client
  222. ledgerwallet >= "0.4.0"
  223. letsencrypt
  224. letsencrypt-app
  225. letsencrypt-dns
  226. letters
  227. lichess_api
  228. links >= "0.9.1"
  229. llama
  230. lru_cache
  231. lwt-canceler
  232. lwt-dllist
  233. lwt-exit
  234. lwt-parallel
  235. lwt-pipe
  236. lwt-pipeline
  237. lwt-watcher
  238. lwt_camlp4
  239. lwt_direct >= "6.0.0~beta01"
  240. lwt_ppx >= "6.0.0~beta01"
  241. lwt_react
  242. lwt_retry
  243. lwt_ssl
  244. mariadb >= "1.2.0"
  245. markdown_monolith
  246. markup = "0.7.6"
  247. markup-lwt
  248. mdx
  249. mechaml
  250. mehari-lwt-unix
  251. mehari-mirage
  252. memtrace-mirage
  253. metrics-influx
  254. metrics-lwt
  255. metrics-unix
  256. mimic
  257. mindstorm-lwt
  258. mirage < "4.0.0"
  259. mirage-block >= "2.0.1"
  260. mirage-block-ccm
  261. mirage-block-combinators
  262. mirage-block-lwt
  263. mirage-block-partition
  264. mirage-block-ramdisk
  265. mirage-block-solo5
  266. mirage-block-unikraft
  267. mirage-block-unix >= "2.14.2"
  268. mirage-block-xen
  269. mirage-channel >= "4.0.1"
  270. mirage-channel-lwt
  271. mirage-clock-lwt
  272. mirage-clock-unix < "4.2.0"
  273. mirage-console-lwt
  274. mirage-crypto-rng < "0.11.3"
  275. mirage-crypto-rng-lwt
  276. mirage-crypto-rng-mirage
  277. mirage-device >= "2.0.0"
  278. mirage-flow >= "3.0.0"
  279. mirage-flow-combinators
  280. mirage-flow-lwt
  281. mirage-flow-unix
  282. mirage-fs >= "4.0.0"
  283. mirage-fs-lwt
  284. mirage-kv >= "3.0.1"
  285. mirage-kv-lwt
  286. mirage-kv-unix
  287. mirage-net >= "4.0.0"
  288. mirage-net-lwt
  289. mirage-net-macosx
  290. mirage-net-solo5
  291. mirage-net-unikraft
  292. mirage-net-unix
  293. mirage-net-xen
  294. mirage-profile
  295. mirage-protocols >= "7.0.0"
  296. mirage-protocols-lwt
  297. mirage-qubes
  298. mirage-qubes-ipv4
  299. mirage-runtime
  300. mirage-sleep
  301. mirage-solo5
  302. mirage-stack = "3.0.0"
  303. mirage-stack-lwt
  304. mirage-time >= "3.0.0"
  305. mirage-time-lwt
  306. mirage-time-unix
  307. mirage-types-lwt
  308. mirage-unikraft
  309. mirage-unix
  310. mirage-vnetif
  311. mirage-xen
  312. monorobot
  313. mqtt
  314. mrmime >= "0.5.0"
  315. multipart-form-data
  316. multipart_form >= "0.2.0" & < "0.4.0"
  317. multipart_form-cohttp-lwt < "0.6.0"
  318. multipart_form-lwt
  319. naboris
  320. nbd >= "4.0.3"
  321. nbd-tool
  322. nbd-unix
  323. neo4j_bolt
  324. nottui-lwt
  325. notty-community
  326. nproc
  327. nsq
  328. obuilder
  329. obus >= "1.2.1"
  330. ocluster-api
  331. ocluster-worker
  332. ocplib-resto
  333. ocsigenserver
  334. ocsipersist
  335. ocsipersist-dbm
  336. ocsipersist-lib
  337. ocsipersist-pgsql
  338. ocsipersist-sqlite
  339. octez-distributed-lwt-internal
  340. octez-internal-libs
  341. octez-l2-libs
  342. octez-libs
  343. octez-proto-libs
  344. octez-protocol-compiler
  345. octez-proxy-server
  346. octez-rpc-process
  347. octez-shell-libs
  348. octez-smart-rollup-wasm-benchmark-lib
  349. oframl
  350. ojs_base
  351. omigrate
  352. oneffs
  353. opam-check-npm-deps >= "4.1.0"
  354. opencage
  355. opentelemetry-client-cohttp-lwt
  356. opentelemetry-cohttp-lwt >= "0.4"
  357. opentelemetry-lwt
  358. opium
  359. opium-graphql
  360. opium_kernel
  361. opomodoro
  362. order-i3-xfce
  363. ordma
  364. oskel >= "0.3.0"
  365. ounit-lwt < "2.2.0"
  366. ounit2-lwt
  367. owork
  368. ozulip
  369. paf
  370. paf-cohttp
  371. passage < "0.1.8"
  372. pcap-format < "0.5.2"
  373. petrol
  374. pgn_parser
  375. pgx_lwt
  376. pgx_lwt_mirage
  377. pgx_lwt_unix < "2.0"
  378. piaf < "0.2.0"
  379. picos_meta
  380. plebeia >= "2.0.0"
  381. plotkicadsch
  382. ppx_defer >= "0.4.0"
  383. ppx_deriving_rpc
  384. ppx_rapper_lwt
  385. proc-smaps
  386. prof_spacetime
  387. prometheus
  388. prometheus-app
  389. promise_jsoo_lwt
  390. protocol-9p
  391. protocol-9p-unix
  392. proton
  393. pxshot
  394. qcow
  395. qcow-stream
  396. qcow-tool
  397. qcow-types
  398. qdrant < "0.2.0"
  399. qfs >= "0.5"
  400. quests
  401. rawlink < "2.1"
  402. rawlink-lwt
  403. rdf_json_ld
  404. rdf_lwt
  405. redis-lwt
  406. reparse-lwt
  407. reparse-lwt-unix
  408. resource-pooling
  409. resp
  410. resp-mirage >= "0.10.0"
  411. resp-unix >= "0.10.0"
  412. resto
  413. resto-cohttp-client >= "0.4"
  414. resto-cohttp-self-serving-client
  415. resto-cohttp-server >= "0.4" & < "0.6" | >= "0.9"
  416. resto-directory >= "0.4"
  417. riak
  418. ringo-lwt
  419. river
  420. rock
  421. rpclib-js
  422. rpclib-lwt
  423. SZXX < "4.0.0"
  424. sanddb
  425. scgi
  426. sendmail-lwt
  427. sendmail-mirage
  428. serial
  429. server-reason-react
  430. session-cohttp-lwt
  431. session-cookie-lwt
  432. session-postgresql-lwt
  433. sessions
  434. shared-block-ring
  435. shared-memory-ring-lwt
  436. sherlodoc
  437. sihl < "0.2.0"
  438. slack
  439. slacko
  440. slipshow
  441. smtml >= "0.7.0"
  442. speed
  443. spin < "0.8.0"
  444. spoke
  445. statocaml
  446. stk
  447. stog
  448. swapfs
  449. syguslib-utils
  450. syndic >= "1.4" & < "1.6.0"
  451. tar-mirage
  452. tar-unix
  453. tcpip
  454. telegraml
  455. terminus
  456. testo-lwt
  457. tezos-base >= "16.0"
  458. tezos-clic >= "16.0"
  459. tezos-crypto >= "16.0"
  460. tezos-crypto-dal
  461. tezos-error-monad >= "16.0"
  462. tezos-lwt-result-stdlib
  463. tezos-p2p = "12.3"
  464. tezos-protocol-environment
  465. tezos-proxy >= "17.3"
  466. tezos-stdlib
  467. tezos-stdlib-unix >= "16.0"
  468. tezos-test-helpers >= "12.3"
  469. tezos-webassembly-interpreter-extra
  470. tidy_email
  471. timmy-lwt
  472. tls >= "0.10.6" & < "0.16.0"
  473. tls-lwt
  474. tls-mirage
  475. tube
  476. tuntap
  477. twirp_cohttp_lwt_unix
  478. uring
  479. uspf
  480. uspf-lwt
  481. uspf-mirage
  482. utop
  483. uwt
  484. vchan
  485. vchan-unix
  486. vchan-xen
  487. vercel
  488. vhd-format-lwt
  489. vmnet
  490. vpnkit
  491. vue-jsoo < "0.3"
  492. wayland < "2.0"
  493. webauthn
  494. xen-evtchn
  495. xen-evtchn-unix
  496. xen-gnt
  497. xen-gnt-unix
  498. xenstore
  499. xenstore-tool
  500. xenstore_transport
  501. xlsx2csv
  502. yocaml_git
  503. yocaml_unix < "2.0.0"
  504. zarr-lwt
  505. zmq-lwt >= "5.2.1"

Conflicts

None