package lwt

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Promises and event-driven I/O

Install 

dune-project
 Dependency

github.com Edit opam file Versions (33)

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. awso-lwt
  20. azure-cosmos-db < "0.4.0"
  21. azure-cosmos-db-lwt
  22. balancer
  23. bastet_lwt
  24. bimage-lwt
  25. bistro
  26. bizowie-api
  27. brisk-reconciler
  28. builder
  29. builder-web
  30. bun >= "0.3.3"
  31. cachet-lwt
  32. calculon
  33. caldav
  34. camltc
  35. canary
  36. capnp-rpc-lwt < "2.0"
  37. capnp-rpc-unix < "2.1"
  38. caqti-lwt < "2.3.0"
  39. caqti-mirage
  40. carton < "1.0.0"
  41. carton-git
  42. carton-lwt
  43. catala-format >= "0.2.0"
  44. cf-lwt
  45. chamelon
  46. chamelon-unix
  47. chamo
  48. charrua-client
  49. charrua-unix
  50. chess_com_api
  51. ciao_lwt
  52. clz
  53. cmdtui-lambda-term
  54. coap
  55. coap-server-lwt
  56. cohttp-curl-lwt
  57. cohttp-lwt
  58. cohttp-lwt-jsoo
  59. cohttp-lwt-unix
  60. cohttp-mirage
  61. cohttp-server-lwt-unix
  62. comby
  63. comby-semantic
  64. conan-lwt
  65. conduit-lwt
  66. conduit-lwt-unix
  67. cowabloga
  68. crunch
  69. cstruct-lwt
  70. csv-lwt
  71. ctypes >= "0.15.0" & < "0.21.1"
  72. ctypes-foreign >= "0.21.1"
  73. curl_lwt
  74. current
  75. current-albatross-deployer
  76. current_docker
  77. current_examples
  78. current_git
  79. current_github
  80. current_gitlab
  81. current_ocluster
  82. current_rpc
  83. current_slack
  84. current_web
  85. dap
  86. data-encoding < "0.1.1"
  87. devkit >= "1.2"
  88. distributed-lwt
  89. dkim-bin < "0.8.0"
  90. dkim-lwt-unix
  91. dkim-mirage
  92. dlm
  93. dmarc
  94. dns-certify
  95. dns-cli
  96. dns-client < "7.0.3"
  97. dns-client-lwt
  98. dns-client-mirage
  99. dns-forward
  100. dns-forward-lwt-unix
  101. dns-lwt
  102. dns-mirage
  103. dns-resolver
  104. dns-server
  105. dns-stub
  106. dnsrobot
  107. dnssd
  108. docker_hub
  109. docteur >= "0.0.2"
  110. docteur-solo5
  111. docteur-unix >= "0.0.5"
  112. doi2bib
  113. dream
  114. dream-httpaf
  115. dream-pure
  116. dream-serve < "1.0.1"
  117. dropbox
  118. dune >= "3.17.2"
  119. dune-rpc-lwt
  120. earlybird
  121. elasticsearch-cli
  122. emoji = "2.0.0"
  123. equinoxe
  124. ethernet
  125. ez_api >= "1.2.0"
  126. ezcurl-lwt
  127. ezjs_min < "0.2"
  128. ezjsonm-lwt
  129. ezresto
  130. faraday-lwt
  131. faraday-lwt-unix
  132. fat-filesystem
  133. fiber-lwt
  134. fsevents-lwt
  135. fswatch_lwt
  136. gdbprofiler
  137. git
  138. git-cohttp
  139. git-cohttp-unix
  140. git-kv >= "0.2.0"
  141. git-mirage
  142. git-paf
  143. git-unix >= "3.2.0"
  144. github
  145. github-hooks
  146. github-unix >= "4.4.0"
  147. gitlab-unix
  148. gitlab_pipeline_notifier
  149. gluten-lwt
  150. gluten-lwt-unix < "0.4.0"
  151. gluten-mirage < "0.4.0"
  152. graphql-lwt
  153. gremlin
  154. grpc-lwt
  155. guardian
  156. gufo
  157. h1
  158. h1-lwt-unix
  159. h2-lwt
  160. h2-lwt-unix < "0.10.0"
  161. h2-mirage
  162. happy-eyeballs-lwt
  163. happy-eyeballs-mirage
  164. hidapi-lwt
  165. hiredis >= "0.6"
  166. hl_yaml
  167. hockmd
  168. http-lwt-client
  169. http-mirage-client
  170. http-multipart-formdata >= "2.0.0" & < "3.0.0"
  171. httpaf-lwt-unix
  172. httpun-lwt
  173. httpun-mirage
  174. httpun-ws-lwt
  175. hvsock
  176. i3ipc
  177. influxdb-lwt
  178. inotify >= "2.4"
  179. inquire < "0.3.0"
  180. interface-prime-lwt
  181. ip2location
  182. ip2locationio
  183. ip2whois
  184. ipv6-multicast-lwt
  185. irc-client-lwt
  186. irc-client-lwt-ssl
  187. irc-client-tls
  188. irmin
  189. irmin-bench
  190. irmin-chunk
  191. irmin-cli
  192. irmin-client
  193. irmin-containers
  194. irmin-fs
  195. irmin-git
  196. irmin-graphql
  197. irmin-http
  198. irmin-indexeddb
  199. irmin-layers
  200. irmin-mirage-git
  201. irmin-mirage-graphql
  202. irmin-pack
  203. irmin-server
  204. irmin-test
  205. irmin-unix
  206. irmin-watcher
  207. joolog
  208. jose < "0.9.0"
  209. js_of_ocaml-lwt
  210. jsoo_broadcastchannel
  211. jsoo_storage
  212. jupyter
  213. jupyter-kernel
  214. kafka < "0.5"
  215. kafka_lwt
  216. kappa-library
  217. ke >= "0.5"
  218. kinetic-client
  219. kubecaml
  220. lambda-runtime
  221. lambda-term >= "3.3.3"
  222. lambda_streams_lwt
  223. launchd
  224. ldp
  225. learn-ocaml
  226. learn-ocaml-client
  227. ledgerwallet >= "0.4.0"
  228. letsencrypt < "2.0.0"
  229. letsencrypt-app
  230. letsencrypt-dns < "2.0.0"
  231. letters
  232. lichess_api
  233. links
  234. llama
  235. lru_cache
  236. lwt-canceler
  237. lwt-dllist
  238. lwt-exit
  239. lwt-parallel
  240. lwt-pipe
  241. lwt-pipeline
  242. lwt-watcher
  243. lwt_camlp4
  244. lwt_direct >= "6.0.0"
  245. lwt_domain != "0.2.0"
  246. lwt_eio >= "0.6"
  247. lwt_ppx >= "6.0.0"
  248. lwt_react
  249. lwt_retry
  250. lwt_ssl
  251. mariadb >= "1.2.0"
  252. markdown_monolith
  253. markup = "0.7.6"
  254. markup-lwt
  255. mdx
  256. mechaml
  257. mehari-lwt-unix
  258. mehari-mirage
  259. memtrace-mirage
  260. metrics-influx
  261. metrics-lwt
  262. metrics-unix
  263. mimic
  264. mindstorm-lwt
  265. mirage < "4.0.0"
  266. mirage-block >= "2.0.1"
  267. mirage-block-ccm
  268. mirage-block-combinators
  269. mirage-block-lwt
  270. mirage-block-partition
  271. mirage-block-ramdisk
  272. mirage-block-solo5
  273. mirage-block-unikraft
  274. mirage-block-unix >= "2.14.2"
  275. mirage-block-xen
  276. mirage-channel >= "4.0.1"
  277. mirage-channel-lwt
  278. mirage-clock-lwt
  279. mirage-clock-unix < "4.2.0"
  280. mirage-console-lwt
  281. mirage-crypto-rng < "0.11.3"
  282. mirage-crypto-rng-lwt
  283. mirage-crypto-rng-mirage
  284. mirage-device >= "2.0.0"
  285. mirage-flow >= "3.0.0"
  286. mirage-flow-combinators
  287. mirage-flow-lwt
  288. mirage-flow-unix
  289. mirage-fs >= "4.0.0"
  290. mirage-fs-lwt
  291. mirage-kv >= "3.0.1"
  292. mirage-kv-lwt
  293. mirage-kv-unix
  294. mirage-net >= "4.0.0"
  295. mirage-net-lwt
  296. mirage-net-macosx
  297. mirage-net-solo5
  298. mirage-net-unikraft
  299. mirage-net-unix
  300. mirage-net-xen
  301. mirage-profile
  302. mirage-protocols >= "7.0.0"
  303. mirage-protocols-lwt
  304. mirage-qubes
  305. mirage-qubes-ipv4
  306. mirage-runtime
  307. mirage-sleep
  308. mirage-solo5
  309. mirage-stack = "3.0.0"
  310. mirage-stack-lwt
  311. mirage-time >= "3.0.0"
  312. mirage-time-lwt
  313. mirage-time-unix
  314. mirage-types-lwt
  315. mirage-unikraft
  316. mirage-unix
  317. mirage-vnetif
  318. mirage-xen
  319. monorobot
  320. mqtt
  321. mrmime >= "0.5.0"
  322. multipart-form-data
  323. multipart_form >= "0.2.0" & < "0.4.0"
  324. multipart_form-cohttp-lwt < "0.6.0"
  325. multipart_form-lwt
  326. naboris
  327. nbd >= "4.0.3"
  328. nbd-tool
  329. nbd-unix
  330. neo4j_bolt
  331. nottui-lwt
  332. notty-community
  333. nproc
  334. nsq
  335. obuilder
  336. obus >= "1.2.1"
  337. ocaml-ai-sdk
  338. ocluster
  339. ocluster-api
  340. ocluster-worker
  341. ocplib-resto
  342. ocsigenserver
  343. ocsipersist
  344. ocsipersist-dbm
  345. ocsipersist-lib
  346. ocsipersist-pgsql
  347. ocsipersist-sqlite
  348. oframl
  349. ojs_base
  350. omigrate
  351. oneffs
  352. opam-check-npm-deps >= "4.1.0"
  353. opam-publish >= "3.0.0"
  354. opencage
  355. opentelemetry-client-cohttp-lwt
  356. opentelemetry-client-ocurl-lwt
  357. opentelemetry-cohttp-lwt >= "0.4"
  358. opentelemetry-lwt
  359. opium
  360. opium-graphql
  361. opium_kernel
  362. opomodoro
  363. order-i3-xfce
  364. ordma
  365. oskel >= "0.3.0"
  366. ounit-lwt < "2.2.0"
  367. ounit2-lwt
  368. owork
  369. ozulip
  370. paf
  371. paf-cohttp
  372. passage < "0.1.8"
  373. pcap-format < "0.5.2"
  374. petrol
  375. pgn_parser
  376. pgx_lwt
  377. pgx_lwt_mirage
  378. pgx_lwt_unix < "2.0"
  379. piaf < "0.2.0"
  380. picos >= "0.3.0" & < "0.5.0"
  381. picos_meta
  382. plebeia >= "2.0.0"
  383. plotkicadsch
  384. posix-getopt >= "4.0.2"
  385. ppx_defer >= "0.4.0"
  386. ppx_deriving_rpc
  387. ppx_rapper_lwt
  388. proc-smaps
  389. prof_spacetime
  390. prometheus
  391. prometheus-app
  392. promise_jsoo_lwt
  393. protocol-9p
  394. protocol-9p-unix
  395. proton
  396. pxshot
  397. qcow
  398. qcow-stream
  399. qcow-tool
  400. qcow-types
  401. qdrant < "0.2.0"
  402. qfs
  403. quests
  404. quickterface
  405. rawlink < "2.1"
  406. rawlink-lwt
  407. rdf_json_ld
  408. rdf_lwt
  409. redis-lwt
  410. reparse-lwt
  411. reparse-lwt-unix
  412. resource-pooling
  413. resp
  414. resp-mirage >= "0.10.0"
  415. resp-unix >= "0.10.0"
  416. resto
  417. resto-cohttp-client = "0.4"
  418. resto-cohttp-server = "0.4"
  419. resto-directory = "0.4"
  420. ringo-lwt
  421. river
  422. rock
  423. rpclib-js
  424. rpclib-lwt
  425. SZXX < "4.0.0"
  426. sanddb
  427. scgi
  428. sendmail-lwt
  429. sendmail-mirage
  430. serial
  431. server-reason-react
  432. session-cohttp-lwt
  433. session-cookie-lwt
  434. session-postgresql-lwt
  435. sessions
  436. shared-block-ring
  437. shared-memory-ring-lwt
  438. sherlodoc
  439. sihl < "0.2.0"
  440. slack
  441. slacko
  442. slipshow
  443. smtml >= "0.7.0"
  444. speed
  445. spin < "0.8.0"
  446. spoke
  447. statocaml
  448. stk
  449. stog
  450. swapfs
  451. syguslib-utils
  452. syndic >= "1.4" & < "1.6.0"
  453. tar-mirage
  454. tar-unix
  455. tcpip
  456. telegraml
  457. terminus
  458. testcontainers
  459. testo-lwt
  460. tidy_email
  461. tls >= "0.10.6" & < "0.16.0"
  462. tls-lwt
  463. tls-mirage
  464. tube
  465. tuntap
  466. twirp_cohttp_lwt_unix
  467. uring
  468. uspf
  469. uspf-lwt
  470. uspf-mirage
  471. utcp
  472. utop
  473. uwt
  474. vchan
  475. vchan-unix
  476. vchan-xen
  477. vercel
  478. vhd-format-lwt
  479. vmnet
  480. vue-jsoo < "0.3"
  481. wayland < "2.0"
  482. webauthn
  483. xen-evtchn
  484. xen-evtchn-unix
  485. xen-gnt
  486. xen-gnt-unix
  487. xenstore
  488. xenstore-tool
  489. xenstore_transport
  490. xlsx2csv
  491. yocaml_git
  492. yocaml_unix < "2.0.0"
  493. zarr-lwt
  494. zmq-lwt >= "5.2.1"

Conflicts

None