package lwt

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Promises and event-driven I/O

Install 

dune-project
 Dependency

github.com Edit opam file Versions (32)

Authors

  1. J
    Jérôme Vouillon
  2. J
    Jérémie Dimino

Maintainers

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

Sources

6.1.2.tar.gz
md5=00bc7eb2772a28530f7365a7040f0c4f
sha512=a4737a2fc44aaeedca46ec6134c07013d5cf44039a988a6e79a40715a53e43601d4c91bbf11a8e89540528d912b8fa487e3068465c136c1156a872258eb3443b

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: 29 Apr 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 dev & >= "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 >= "4.8.1"
  18. awsm-lwt
  19. azure-cosmos-db < "0.4.0"
  20. azure-cosmos-db-lwt
  21. balancer
  22. bastet_lwt
  23. bistro
  24. brisk-reconciler
  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. ciao_lwt
  48. clz
  49. cmdtui-lambda-term
  50. coap
  51. coap-server-lwt
  52. cohttp-curl-lwt
  53. cohttp-lwt
  54. cohttp-lwt-jsoo
  55. cohttp-lwt-unix
  56. cohttp-mirage
  57. cohttp-server-lwt-unix
  58. comby
  59. comby-semantic
  60. conan-lwt
  61. conduit-lwt
  62. conduit-lwt-unix
  63. cowabloga
  64. crunch
  65. cstruct-lwt
  66. csv-lwt
  67. ctypes >= "0.15.0" & < "0.21.1"
  68. ctypes-foreign >= "0.21.1"
  69. curl_lwt
  70. current
  71. current-albatross-deployer
  72. current_docker
  73. current_examples
  74. current_git
  75. current_github
  76. current_gitlab
  77. current_ocluster
  78. current_rpc
  79. current_slack
  80. current_web
  81. dap
  82. data-encoding < "0.1.1"
  83. devkit >= "1.2"
  84. distributed-lwt
  85. dkim-bin < "0.8.0"
  86. dkim-lwt-unix
  87. dkim-mirage
  88. dlm
  89. dmarc
  90. dns-certify
  91. dns-cli
  92. dns-client < "7.0.3"
  93. dns-client-lwt
  94. dns-client-mirage
  95. dns-forward
  96. dns-forward-lwt-unix
  97. dns-lwt
  98. dns-mirage
  99. dns-resolver
  100. dns-server
  101. dns-stub
  102. dnsrobot
  103. dnssd
  104. docker_hub
  105. docteur >= "0.0.2"
  106. docteur-solo5
  107. docteur-unix >= "0.0.5"
  108. doi2bib
  109. dream
  110. dream-httpaf
  111. dream-pure
  112. dream-serve
  113. dropbox
  114. dune >= "3.17.2"
  115. dune-rpc-lwt
  116. earlybird
  117. elasticsearch-cli
  118. emoji = "2.0.0"
  119. equinoxe
  120. ethernet
  121. ez_api >= "1.2.0"
  122. ezcurl-lwt
  123. ezjs_min < "0.2"
  124. ezjsonm-lwt
  125. ezresto
  126. faraday-lwt
  127. faraday-lwt-unix
  128. fat-filesystem
  129. fiber-lwt
  130. fsevents-lwt
  131. fswatch_lwt
  132. gdbprofiler
  133. git
  134. git-cohttp
  135. git-cohttp-unix
  136. git-kv >= "0.2.0"
  137. git-mirage
  138. git-paf
  139. git-unix >= "3.2.0"
  140. github
  141. github-hooks
  142. github-unix >= "4.4.0"
  143. gitlab-unix
  144. gitlab_pipeline_notifier
  145. gluten-lwt
  146. gluten-lwt-unix < "0.4.0"
  147. gluten-mirage < "0.4.0"
  148. graphql-lwt
  149. gremlin
  150. grpc-lwt
  151. guardian
  152. gufo
  153. h1
  154. h1-lwt-unix
  155. h2-lwt
  156. h2-lwt-unix < "0.10.0"
  157. h2-mirage
  158. happy-eyeballs-lwt
  159. happy-eyeballs-mirage
  160. hidapi-lwt
  161. hiredis >= "0.6"
  162. hl_yaml
  163. hockmd
  164. http-lwt-client
  165. http-mirage-client
  166. http-multipart-formdata >= "2.0.0" & < "3.0.0"
  167. httpaf-lwt-unix
  168. httpun-lwt
  169. httpun-mirage
  170. httpun-ws-lwt
  171. hvsock
  172. i3ipc
  173. influxdb-lwt
  174. inotify >= "2.4"
  175. inquire < "0.3.0"
  176. interface-prime-lwt
  177. ip2location
  178. ip2locationio
  179. ip2whois
  180. ipv6-multicast-lwt
  181. irc-client-lwt
  182. irc-client-lwt-ssl
  183. irc-client-tls
  184. irmin
  185. irmin-bench
  186. irmin-chunk
  187. irmin-cli
  188. irmin-client
  189. irmin-containers
  190. irmin-fs
  191. irmin-git
  192. irmin-graphql
  193. irmin-http
  194. irmin-indexeddb
  195. irmin-layers
  196. irmin-mirage-git
  197. irmin-mirage-graphql
  198. irmin-pack
  199. irmin-server
  200. irmin-test
  201. irmin-unix
  202. irmin-watcher
  203. joolog
  204. jose < "0.9.0"
  205. js_of_ocaml-lwt
  206. jsoo_broadcastchannel
  207. jsoo_storage
  208. jupyter
  209. jupyter-kernel
  210. kafka < "0.5"
  211. kafka_lwt
  212. kappa-library
  213. ke >= "0.5"
  214. kinetic-client
  215. kubecaml
  216. lambda-runtime
  217. lambda-term >= "3.3.3"
  218. lambda_streams_lwt
  219. launchd
  220. ldp
  221. learn-ocaml
  222. learn-ocaml-client
  223. ledgerwallet >= "0.4.0"
  224. letsencrypt < "2.0.0"
  225. letsencrypt-app
  226. letsencrypt-dns < "2.0.0"
  227. letters
  228. lichess_api
  229. links
  230. llama
  231. lru_cache
  232. lwt-canceler
  233. lwt-dllist
  234. lwt-exit
  235. lwt-parallel
  236. lwt-pipe
  237. lwt-pipeline
  238. lwt-watcher
  239. lwt_camlp4
  240. lwt_direct >= "6.0.0"
  241. lwt_eio >= "0.6"
  242. lwt_ppx >= "6.0.0"
  243. lwt_react
  244. lwt_retry
  245. lwt_ssl
  246. mariadb >= "1.2.0"
  247. markdown_monolith
  248. markup = "0.7.6"
  249. markup-lwt
  250. mdx
  251. mechaml
  252. mehari-lwt-unix
  253. mehari-mirage
  254. memtrace-mirage
  255. metrics-influx
  256. metrics-lwt
  257. metrics-unix
  258. mimic
  259. mindstorm-lwt
  260. mirage < "4.0.0"
  261. mirage-block >= "2.0.1"
  262. mirage-block-ccm
  263. mirage-block-combinators
  264. mirage-block-lwt
  265. mirage-block-partition
  266. mirage-block-ramdisk
  267. mirage-block-solo5
  268. mirage-block-unikraft
  269. mirage-block-unix >= "2.14.2"
  270. mirage-block-xen
  271. mirage-channel >= "4.0.1"
  272. mirage-channel-lwt
  273. mirage-clock-lwt
  274. mirage-clock-unix < "4.2.0"
  275. mirage-console-lwt
  276. mirage-crypto-rng < "0.11.3"
  277. mirage-crypto-rng-lwt
  278. mirage-crypto-rng-mirage
  279. mirage-device >= "2.0.0"
  280. mirage-flow >= "3.0.0"
  281. mirage-flow-combinators
  282. mirage-flow-lwt
  283. mirage-flow-unix
  284. mirage-fs >= "4.0.0"
  285. mirage-fs-lwt
  286. mirage-kv >= "3.0.1"
  287. mirage-kv-lwt
  288. mirage-kv-unix
  289. mirage-net >= "4.0.0"
  290. mirage-net-lwt
  291. mirage-net-macosx
  292. mirage-net-solo5
  293. mirage-net-unikraft
  294. mirage-net-unix
  295. mirage-net-xen
  296. mirage-profile
  297. mirage-protocols >= "7.0.0"
  298. mirage-protocols-lwt
  299. mirage-qubes
  300. mirage-qubes-ipv4
  301. mirage-runtime
  302. mirage-sleep
  303. mirage-solo5
  304. mirage-stack = "3.0.0"
  305. mirage-stack-lwt
  306. mirage-time >= "3.0.0"
  307. mirage-time-lwt
  308. mirage-time-unix
  309. mirage-types-lwt
  310. mirage-unikraft
  311. mirage-unix
  312. mirage-vnetif
  313. mirage-xen
  314. monorobot
  315. mqtt
  316. mrmime >= "0.5.0"
  317. multipart-form-data
  318. multipart_form >= "0.2.0" & < "0.4.0"
  319. multipart_form-cohttp-lwt < "0.6.0"
  320. multipart_form-lwt
  321. naboris
  322. nbd >= "4.0.3"
  323. nbd-tool
  324. nbd-unix
  325. neo4j_bolt
  326. nottui-lwt
  327. notty-community
  328. nproc
  329. nsq
  330. obuilder
  331. obus >= "1.2.1"
  332. ocaml-ai-sdk
  333. ocluster-api
  334. ocluster-worker
  335. ocplib-resto
  336. ocsigenserver
  337. ocsipersist
  338. ocsipersist-dbm
  339. ocsipersist-lib
  340. ocsipersist-pgsql
  341. ocsipersist-sqlite
  342. oframl
  343. ojs_base
  344. omigrate
  345. oneffs
  346. opam-check-npm-deps >= "4.1.0"
  347. opam-publish >= "3.0.0"
  348. opencage
  349. opentelemetry-client-cohttp-lwt
  350. opentelemetry-client-ocurl-lwt
  351. opentelemetry-cohttp-lwt >= "0.4"
  352. opentelemetry-lwt
  353. opium
  354. opium-graphql
  355. opium_kernel
  356. opomodoro
  357. order-i3-xfce
  358. ordma
  359. oskel >= "0.3.0"
  360. ounit-lwt < "2.2.0"
  361. ounit2-lwt
  362. owork
  363. ozulip
  364. paf
  365. paf-cohttp
  366. passage < "0.1.8"
  367. pcap-format < "0.5.2"
  368. petrol
  369. pgn_parser
  370. pgx_lwt
  371. pgx_lwt_mirage
  372. pgx_lwt_unix < "2.0"
  373. piaf < "0.2.0"
  374. picos_meta
  375. plebeia >= "2.0.0"
  376. plotkicadsch
  377. posix-getopt >= "4.0.2"
  378. ppx_defer >= "0.4.0"
  379. ppx_deriving_rpc
  380. ppx_rapper_lwt
  381. proc-smaps
  382. prof_spacetime
  383. prometheus
  384. prometheus-app
  385. promise_jsoo_lwt
  386. protocol-9p
  387. protocol-9p-unix
  388. proton
  389. pxshot
  390. qcow
  391. qcow-stream
  392. qcow-tool
  393. qcow-types
  394. qdrant < "0.2.0"
  395. qfs
  396. quests
  397. quickterface
  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. ringo-lwt
  414. river
  415. rock
  416. rpclib-js
  417. rpclib-lwt
  418. SZXX < "4.0.0"
  419. sanddb
  420. scgi
  421. sendmail-lwt
  422. sendmail-mirage
  423. serial
  424. server-reason-react
  425. session-cohttp-lwt
  426. session-cookie-lwt
  427. session-postgresql-lwt
  428. sessions
  429. shared-block-ring
  430. shared-memory-ring-lwt
  431. sherlodoc
  432. sihl < "0.2.0"
  433. slack
  434. slacko
  435. slipshow
  436. smtml >= "0.7.0"
  437. speed
  438. spin < "0.8.0"
  439. spoke
  440. statocaml
  441. stk
  442. stog
  443. swapfs
  444. syguslib-utils
  445. syndic >= "1.4" & < "1.6.0"
  446. tar-mirage
  447. tar-unix
  448. tcpip
  449. telegraml
  450. terminus
  451. testcontainers
  452. testo-lwt
  453. tidy_email
  454. tls >= "0.10.6" & < "0.16.0"
  455. tls-lwt
  456. tls-mirage
  457. tube
  458. tuntap
  459. twirp_cohttp_lwt_unix
  460. uring
  461. uspf
  462. uspf-lwt
  463. uspf-mirage
  464. utcp
  465. utop
  466. uwt
  467. vchan
  468. vchan-unix
  469. vchan-xen
  470. vercel
  471. vhd-format-lwt
  472. vmnet
  473. vue-jsoo < "0.3"
  474. wayland < "2.0"
  475. webauthn
  476. xen-evtchn
  477. xen-evtchn-unix
  478. xen-gnt
  479. xen-gnt-unix
  480. xenstore
  481. xenstore-tool
  482. xenstore_transport
  483. xlsx2csv
  484. yocaml_git
  485. yocaml_unix < "2.0.0"
  486. zarr-lwt
  487. zmq-lwt >= "5.2.1"

Conflicts

None