package lwt

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Promises and event-driven I/O

Install 

dune-project
 Dependency

github.com Edit opam file Versions (29)

Authors

  1. J
    Jérôme Vouillon
  2. J
    Jérémie Dimino

Maintainers

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

Sources

6.0.0.tar.gz
md5=8bfdd7b36a40fc715c48b3a9edccf324
sha512=6d2f4866e06601f9e7e43ac6378f05a3ea915c94548d5a6c96e2fb2adc2c6cff233ffa56862ca7be809c2d2114ed9335c22fb7d768adf7fae5460bb52de3f938

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: 12 Jan 2026

Dependencies (5)

  1. ocplib-endian
  2. dune-configurator
  3. cppo build & >= "1.1"
  4. ocaml >= "4.14"
  5. dune >= "3.18"

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. faraday-lwt
  125. faraday-lwt-unix
  126. fat-filesystem
  127. fiber-lwt
  128. fsevents-lwt
  129. fswatch_lwt
  130. gdbprofiler
  131. git
  132. git-cohttp
  133. git-cohttp-unix
  134. git-kv >= "0.2.0"
  135. git-mirage
  136. git-paf
  137. git-unix >= "3.2.0"
  138. github
  139. github-hooks
  140. github-unix >= "4.4.0"
  141. gitlab-unix
  142. gitlab_pipeline_notifier
  143. gluten-lwt
  144. gluten-lwt-unix < "0.4.0"
  145. gluten-mirage < "0.4.0"
  146. graphql-lwt
  147. gremlin
  148. grpc-lwt
  149. guardian
  150. gufo
  151. h1
  152. h1-lwt-unix
  153. h2-lwt
  154. h2-lwt-unix < "0.10.0"
  155. h2-mirage
  156. happy-eyeballs-lwt
  157. happy-eyeballs-mirage
  158. hidapi-lwt
  159. hiredis >= "0.6"
  160. hl_yaml
  161. hockmd
  162. http-lwt-client
  163. http-mirage-client
  164. http-multipart-formdata >= "2.0.0" & < "3.0.0"
  165. httpaf-lwt-unix
  166. httpun-lwt
  167. httpun-mirage
  168. httpun-ws-lwt
  169. hvsock
  170. i3ipc
  171. influxdb-lwt
  172. inotify >= "2.4"
  173. inquire < "0.3.0"
  174. interface-prime-lwt
  175. ip2location
  176. ip2locationio
  177. ip2whois
  178. ipv6-multicast-lwt
  179. irc-client-lwt
  180. irc-client-lwt-ssl
  181. irc-client-tls
  182. irmin
  183. irmin-bench
  184. irmin-chunk
  185. irmin-cli
  186. irmin-client
  187. irmin-containers
  188. irmin-fs
  189. irmin-git
  190. irmin-graphql
  191. irmin-http
  192. irmin-indexeddb
  193. irmin-layers
  194. irmin-mirage-git
  195. irmin-mirage-graphql
  196. irmin-pack
  197. irmin-server
  198. irmin-test
  199. irmin-unix
  200. irmin-watcher
  201. joolog
  202. jose < "0.9.0"
  203. js_of_ocaml-lwt >= "3.5.0"
  204. jsoo_broadcastchannel
  205. jsoo_storage
  206. jupyter
  207. jupyter-kernel
  208. kafka < "0.5"
  209. kafka_lwt
  210. kappa-library
  211. ke >= "0.5"
  212. kinetic-client
  213. kubecaml
  214. lambda-runtime
  215. lambda-term >= "3.3.3"
  216. lambda_streams_lwt
  217. launchd
  218. ldp
  219. learn-ocaml
  220. learn-ocaml-client
  221. ledgerwallet >= "0.4.0"
  222. letsencrypt
  223. letsencrypt-app
  224. letsencrypt-dns
  225. letters
  226. lichess_api
  227. links >= "0.9.1"
  228. llama
  229. lru_cache
  230. lwt-canceler
  231. lwt-dllist
  232. lwt-exit
  233. lwt-parallel
  234. lwt-pipe
  235. lwt-pipeline
  236. lwt-watcher
  237. lwt_camlp4
  238. lwt_direct
  239. lwt_ppx = "6.0.0"
  240. lwt_react
  241. lwt_retry
  242. lwt_ssl
  243. mariadb >= "1.2.0"
  244. markdown_monolith
  245. markup = "0.7.6"
  246. markup-lwt
  247. mdx
  248. mechaml
  249. mehari-lwt-unix
  250. mehari-mirage
  251. memtrace-mirage
  252. metrics-influx
  253. metrics-lwt
  254. metrics-unix
  255. mimic
  256. mindstorm-lwt
  257. mirage < "4.0.0"
  258. mirage-block >= "2.0.1"
  259. mirage-block-ccm
  260. mirage-block-combinators
  261. mirage-block-lwt
  262. mirage-block-partition
  263. mirage-block-ramdisk
  264. mirage-block-solo5
  265. mirage-block-unikraft
  266. mirage-block-unix >= "2.14.2"
  267. mirage-block-xen
  268. mirage-channel >= "4.0.1"
  269. mirage-channel-lwt
  270. mirage-clock-lwt
  271. mirage-clock-unix < "4.2.0"
  272. mirage-console-lwt
  273. mirage-crypto-rng < "0.11.3"
  274. mirage-crypto-rng-lwt
  275. mirage-crypto-rng-mirage
  276. mirage-device >= "2.0.0"
  277. mirage-flow >= "3.0.0"
  278. mirage-flow-combinators
  279. mirage-flow-lwt
  280. mirage-flow-unix
  281. mirage-fs >= "4.0.0"
  282. mirage-fs-lwt
  283. mirage-kv >= "3.0.1"
  284. mirage-kv-lwt
  285. mirage-kv-unix
  286. mirage-net >= "4.0.0"
  287. mirage-net-lwt
  288. mirage-net-macosx
  289. mirage-net-solo5
  290. mirage-net-unikraft
  291. mirage-net-unix
  292. mirage-net-xen
  293. mirage-profile
  294. mirage-protocols >= "7.0.0"
  295. mirage-protocols-lwt
  296. mirage-qubes
  297. mirage-qubes-ipv4
  298. mirage-sleep
  299. mirage-solo5
  300. mirage-stack = "3.0.0"
  301. mirage-stack-lwt
  302. mirage-time >= "3.0.0"
  303. mirage-time-lwt
  304. mirage-time-unix
  305. mirage-types-lwt
  306. mirage-unikraft
  307. mirage-unix
  308. mirage-vnetif
  309. mirage-xen
  310. monorobot
  311. mqtt
  312. mrmime >= "0.5.0"
  313. multipart-form-data
  314. multipart_form >= "0.2.0" & < "0.4.0"
  315. multipart_form-cohttp-lwt < "0.6.0"
  316. multipart_form-lwt
  317. naboris
  318. nbd >= "4.0.3"
  319. nbd-tool
  320. nbd-unix
  321. neo4j_bolt
  322. nottui-lwt
  323. notty-community
  324. nproc
  325. nsq
  326. obuilder
  327. obus >= "1.2.1"
  328. ocluster-api
  329. ocluster-worker
  330. ocplib-resto
  331. ocsigenserver
  332. ocsipersist
  333. ocsipersist-dbm
  334. ocsipersist-lib
  335. ocsipersist-pgsql
  336. ocsipersist-sqlite
  337. octez-distributed-lwt-internal
  338. octez-internal-libs
  339. octez-l2-libs
  340. octez-libs
  341. octez-proto-libs
  342. octez-protocol-compiler
  343. octez-proxy-server
  344. octez-rpc-process
  345. octez-shell-libs
  346. octez-smart-rollup-wasm-benchmark-lib
  347. oframl
  348. ojs_base
  349. omigrate
  350. oneffs
  351. opam-check-npm-deps >= "4.1.0"
  352. opencage
  353. opentelemetry-client-cohttp-lwt
  354. opentelemetry-cohttp-lwt >= "0.4"
  355. opentelemetry-lwt
  356. opium
  357. opium-graphql
  358. opium_kernel
  359. opomodoro
  360. order-i3-xfce
  361. ordma
  362. oskel >= "0.3.0"
  363. ounit-lwt < "2.2.0"
  364. ounit2-lwt
  365. owork
  366. ozulip
  367. paf
  368. paf-cohttp
  369. passage < "0.1.8"
  370. pcap-format < "0.5.2"
  371. petrol
  372. pgn_parser
  373. pgx_lwt
  374. pgx_lwt_mirage
  375. pgx_lwt_unix < "2.0"
  376. piaf < "0.2.0"
  377. picos_meta
  378. plebeia >= "2.0.0"
  379. plotkicadsch
  380. ppx_defer >= "0.4.0"
  381. ppx_deriving_rpc
  382. ppx_rapper_lwt
  383. proc-smaps
  384. prof_spacetime
  385. prometheus
  386. prometheus-app
  387. promise_jsoo_lwt
  388. protocol-9p
  389. protocol-9p-unix
  390. proton
  391. qcow
  392. qcow-stream
  393. qcow-tool
  394. qcow-types
  395. qdrant < "0.2.0"
  396. qfs >= "0.5"
  397. quests
  398. rawlink < "2.1"
  399. rawlink-lwt
  400. rdf_json_ld
  401. rdf_lwt
  402. redis-lwt
  403. reparse-lwt
  404. reparse-lwt-unix
  405. resource-pooling
  406. resp
  407. resp-mirage >= "0.10.0"
  408. resp-unix >= "0.10.0"
  409. resto
  410. resto-cohttp-client = "0.4"
  411. resto-cohttp-server = "0.4"
  412. resto-directory = "0.4"
  413. riak
  414. ringo-lwt
  415. river
  416. rock
  417. rpclib-js
  418. rpclib-lwt
  419. SZXX < "4.0.0"
  420. sanddb
  421. scgi
  422. sendmail-lwt
  423. sendmail-mirage
  424. serial
  425. server-reason-react
  426. session-cohttp-lwt
  427. session-cookie-lwt
  428. session-postgresql-lwt
  429. sessions
  430. shared-block-ring
  431. shared-memory-ring-lwt
  432. sherlodoc
  433. sihl < "0.2.0"
  434. slack
  435. slacko
  436. slipshow
  437. smtml >= "0.7.0"
  438. speed
  439. spin < "0.8.0"
  440. spoke
  441. statocaml
  442. stk
  443. stog
  444. swapfs
  445. syguslib-utils
  446. syndic >= "1.4" & < "1.6.0"
  447. tar-mirage
  448. tar-unix
  449. tcpip
  450. telegraml
  451. terminus
  452. testo-lwt
  453. tezos-base >= "16.0"
  454. tezos-clic >= "16.0"
  455. tezos-crypto >= "16.0"
  456. tezos-crypto-dal
  457. tezos-error-monad >= "16.0"
  458. tezos-lwt-result-stdlib
  459. tezos-p2p = "12.3"
  460. tezos-protocol-environment
  461. tezos-proxy >= "17.3"
  462. tezos-stdlib
  463. tezos-stdlib-unix >= "16.0"
  464. tezos-test-helpers >= "12.3"
  465. tezos-webassembly-interpreter-extra
  466. tidy_email
  467. timmy-lwt
  468. tls >= "0.10.6" & < "0.16.0"
  469. tls-lwt
  470. tls-mirage
  471. tube
  472. tuntap
  473. twirp_cohttp_lwt_unix
  474. uring
  475. uspf
  476. uspf-lwt
  477. uspf-mirage
  478. utop
  479. uwt
  480. vchan
  481. vchan-unix
  482. vchan-xen
  483. vercel
  484. vhd-format-lwt
  485. vmnet
  486. vpnkit
  487. vue-jsoo < "0.3"
  488. wayland < "2.0"
  489. webauthn
  490. xen-evtchn
  491. xen-evtchn-unix
  492. xen-gnt
  493. xen-gnt-unix
  494. xenstore
  495. xenstore-tool
  496. xenstore_transport
  497. xlsx2csv
  498. yocaml_git
  499. yocaml_unix < "2.0.0"
  500. zarr-lwt
  501. zmq-lwt >= "5.2.1"

Conflicts

None