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. awskit-lwt
  19. awskit-lwt-unix
  20. awskit-s3-lwt
  21. awskit-s3-lwt-unix
  22. awsm-lwt
  23. awso-lwt
  24. azure-cosmos-db < "0.4.0"
  25. azure-cosmos-db-lwt
  26. balancer
  27. bastet_lwt
  28. bimage-lwt
  29. bistro
  30. bizowie-api
  31. brisk-reconciler
  32. builder
  33. builder-web
  34. bun >= "0.3.3"
  35. cachet-lwt
  36. calculon
  37. caldav
  38. camltc
  39. canary
  40. capnp-rpc-lwt < "2.0"
  41. capnp-rpc-unix < "2.1"
  42. caqti-lwt
  43. caqti-mirage
  44. carton < "1.0.0"
  45. carton-git
  46. carton-lwt
  47. catala-format >= "0.2.0"
  48. cf-lwt
  49. chamelon
  50. chamelon-unix
  51. chamo
  52. charrua-client
  53. charrua-unix
  54. chess_com_api
  55. ciao_lwt
  56. clz
  57. cmdtui-lambda-term
  58. coap
  59. coap-server-lwt
  60. cohttp-curl-lwt
  61. cohttp-lwt
  62. cohttp-lwt-jsoo
  63. cohttp-lwt-unix
  64. cohttp-mirage
  65. cohttp-server-lwt-unix
  66. comby
  67. comby-semantic
  68. conan-lwt
  69. conduit-lwt
  70. conduit-lwt-unix
  71. cowabloga
  72. crunch
  73. cstruct-lwt
  74. csv-lwt
  75. ctypes >= "0.15.0" & < "0.21.1"
  76. ctypes-foreign >= "0.21.1"
  77. curl_lwt
  78. current
  79. current-albatross-deployer
  80. current_docker
  81. current_examples
  82. current_git
  83. current_github
  84. current_gitlab
  85. current_ocluster
  86. current_rpc
  87. current_slack
  88. current_web
  89. dap
  90. data-encoding < "0.1.1"
  91. devkit >= "1.2"
  92. distributed-lwt
  93. dkim-bin < "0.8.0"
  94. dkim-lwt-unix
  95. dkim-mirage
  96. dlm
  97. dmarc
  98. dns-certify
  99. dns-cli
  100. dns-client < "7.0.3"
  101. dns-client-lwt
  102. dns-client-mirage
  103. dns-forward
  104. dns-forward-lwt-unix
  105. dns-lwt
  106. dns-mirage
  107. dns-resolver
  108. dns-server
  109. dns-stub
  110. dnsrobot
  111. dnssd
  112. docker_hub
  113. docteur >= "0.0.2"
  114. docteur-solo5
  115. docteur-unix >= "0.0.5"
  116. doi2bib
  117. dream
  118. dream-httpaf
  119. dream-pure
  120. dream-serve < "1.0.1"
  121. dropbox
  122. dune >= "3.17.2"
  123. dune-rpc-lwt
  124. earlybird
  125. elasticsearch-cli
  126. emoji = "2.0.0"
  127. equinoxe
  128. ethernet
  129. ez_api >= "1.2.0" & < "3.0.0"
  130. ezcurl-lwt
  131. ezjs_min < "0.2"
  132. ezjsonm-lwt
  133. ezresto
  134. faraday-lwt
  135. faraday-lwt-unix
  136. fat-filesystem
  137. fiber-lwt
  138. fsevents-lwt
  139. fswatch_lwt
  140. gdbprofiler
  141. git
  142. git-cohttp
  143. git-cohttp-unix
  144. git-kv >= "0.2.0"
  145. git-mirage
  146. git-paf
  147. git-unix >= "3.2.0"
  148. github
  149. github-hooks
  150. github-unix >= "4.4.0"
  151. gitlab-unix
  152. gitlab_pipeline_notifier
  153. gluten-lwt
  154. gluten-lwt-unix < "0.4.0"
  155. gluten-mirage < "0.4.0"
  156. graphql-lwt
  157. gremlin
  158. grpc-lwt
  159. guardian
  160. gufo
  161. h1
  162. h1-lwt-unix
  163. h2-lwt
  164. h2-lwt-unix < "0.10.0"
  165. h2-mirage
  166. happy-eyeballs-lwt
  167. happy-eyeballs-mirage
  168. hidapi-lwt
  169. hiredis >= "0.6"
  170. hl_yaml
  171. hockmd
  172. http-lwt-client
  173. http-mirage-client
  174. http-multipart-formdata >= "2.0.0" & < "3.0.0"
  175. httpaf-lwt-unix
  176. httpun-lwt
  177. httpun-mirage
  178. httpun-ws-lwt
  179. hvsock
  180. i3ipc
  181. influxdb-lwt
  182. inotify >= "2.4"
  183. inquire < "0.3.0"
  184. interface-prime-lwt
  185. ip2location
  186. ip2locationio
  187. ip2whois
  188. ipv6-multicast-lwt
  189. irc-client-lwt
  190. irc-client-lwt-ssl
  191. irc-client-tls
  192. irmin
  193. irmin-bench
  194. irmin-chunk
  195. irmin-cli
  196. irmin-client
  197. irmin-containers
  198. irmin-fs
  199. irmin-git
  200. irmin-graphql
  201. irmin-http
  202. irmin-indexeddb
  203. irmin-layers
  204. irmin-mirage-git
  205. irmin-mirage-graphql
  206. irmin-pack
  207. irmin-server
  208. irmin-test
  209. irmin-unix
  210. irmin-watcher
  211. joolog
  212. jose < "0.9.0"
  213. js_of_ocaml-lwt
  214. jsoo_broadcastchannel
  215. jsoo_storage
  216. jupyter
  217. jupyter-kernel
  218. kafka < "0.5"
  219. kafka_lwt
  220. kappa-library
  221. ke >= "0.5"
  222. kinetic-client
  223. kubecaml
  224. lambda-runtime
  225. lambda-term >= "3.3.3"
  226. lambda_streams_lwt
  227. launchd
  228. ldp
  229. learn-ocaml
  230. learn-ocaml-client
  231. ledgerwallet >= "0.4.0"
  232. letsencrypt < "2.0.0"
  233. letsencrypt-app
  234. letsencrypt-dns < "2.0.0"
  235. letters
  236. lichess_api
  237. links
  238. llama
  239. lru_cache
  240. lwt-canceler
  241. lwt-dllist
  242. lwt-exit
  243. lwt-parallel
  244. lwt-pipe
  245. lwt-pipeline
  246. lwt-watcher
  247. lwt_camlp4
  248. lwt_direct >= "6.0.0"
  249. lwt_domain != "0.2.0"
  250. lwt_eio >= "0.6"
  251. lwt_ppx >= "6.0.0"
  252. lwt_react
  253. lwt_retry
  254. lwt_ssl
  255. mariadb >= "1.2.0"
  256. markdown_monolith
  257. markup = "0.7.6"
  258. markup-lwt
  259. mdx
  260. mechaml
  261. mehari-lwt-unix
  262. mehari-mirage
  263. memtrace-mirage
  264. metrics-influx
  265. metrics-lwt
  266. metrics-unix
  267. migra
  268. mimic
  269. mindstorm-lwt
  270. mirage < "4.0.0"
  271. mirage-block >= "2.0.1"
  272. mirage-block-ccm
  273. mirage-block-combinators
  274. mirage-block-lwt
  275. mirage-block-partition
  276. mirage-block-ramdisk
  277. mirage-block-solo5
  278. mirage-block-unikraft
  279. mirage-block-unix >= "2.14.2"
  280. mirage-block-xen
  281. mirage-channel >= "4.0.1"
  282. mirage-channel-lwt
  283. mirage-clock-lwt
  284. mirage-clock-unix < "4.2.0"
  285. mirage-console-lwt
  286. mirage-crypto-rng < "0.11.3"
  287. mirage-crypto-rng-lwt
  288. mirage-crypto-rng-mirage
  289. mirage-device >= "2.0.0"
  290. mirage-flow >= "3.0.0"
  291. mirage-flow-combinators
  292. mirage-flow-lwt
  293. mirage-flow-unix
  294. mirage-fs >= "4.0.0"
  295. mirage-fs-lwt
  296. mirage-kv >= "3.0.1"
  297. mirage-kv-lwt
  298. mirage-kv-unix
  299. mirage-net >= "4.0.0"
  300. mirage-net-lwt
  301. mirage-net-macosx
  302. mirage-net-solo5
  303. mirage-net-unikraft
  304. mirage-net-unix
  305. mirage-net-xen
  306. mirage-profile
  307. mirage-protocols >= "7.0.0"
  308. mirage-protocols-lwt
  309. mirage-qubes
  310. mirage-qubes-ipv4
  311. mirage-runtime
  312. mirage-sleep
  313. mirage-solo5
  314. mirage-stack = "3.0.0"
  315. mirage-stack-lwt
  316. mirage-time >= "3.0.0"
  317. mirage-time-lwt
  318. mirage-time-unix
  319. mirage-types-lwt
  320. mirage-unikraft
  321. mirage-unix
  322. mirage-vnetif
  323. mirage-xen
  324. monorobot
  325. mqtt
  326. mrmime >= "0.5.0"
  327. multipart-form-data
  328. multipart_form >= "0.2.0" & < "0.4.0"
  329. multipart_form-cohttp-lwt < "0.6.0"
  330. multipart_form-lwt
  331. naboris
  332. nbd >= "4.0.3"
  333. nbd-tool
  334. nbd-unix
  335. neo4j_bolt
  336. nottui-lwt
  337. notty-community
  338. nproc
  339. nsq
  340. obuilder
  341. obus >= "1.2.1"
  342. ocaml-ai-sdk
  343. ocluster
  344. ocluster-api
  345. ocluster-worker
  346. ocplib-resto
  347. ocsigenserver
  348. ocsipersist
  349. ocsipersist-dbm
  350. ocsipersist-lib
  351. ocsipersist-pgsql
  352. ocsipersist-sqlite
  353. oframl
  354. ojs_base
  355. omigrate
  356. oneffs
  357. opam-check-npm-deps >= "4.1.0"
  358. opam-publish >= "3.0.0"
  359. opencage
  360. opentelemetry-client-cohttp-lwt
  361. opentelemetry-client-ocurl-lwt
  362. opentelemetry-cohttp-lwt >= "0.4"
  363. opentelemetry-lwt
  364. opium
  365. opium-graphql
  366. opium_kernel
  367. opomodoro
  368. order-i3-xfce
  369. ordma
  370. oskel >= "0.3.0"
  371. ounit-lwt < "2.2.0"
  372. ounit2-lwt
  373. owork
  374. ozulip
  375. paf
  376. paf-cohttp
  377. passage < "0.1.8"
  378. pcap-format < "0.5.2"
  379. petrol
  380. pgn_parser
  381. pgx_lwt
  382. pgx_lwt_mirage
  383. pgx_lwt_unix < "2.0"
  384. piaf < "0.2.0"
  385. picos >= "0.3.0" & < "0.5.0"
  386. picos_meta
  387. plebeia >= "2.0.0"
  388. plotkicadsch
  389. posix-getopt >= "4.0.2"
  390. ppx_defer >= "0.4.0"
  391. ppx_deriving_rpc
  392. ppx_rapper_lwt
  393. proc-smaps
  394. prof_spacetime
  395. prometheus
  396. prometheus-app
  397. promise_jsoo_lwt
  398. protocol-9p
  399. protocol-9p-unix
  400. proton
  401. pxshot
  402. qcow
  403. qcow-stream
  404. qcow-tool
  405. qcow-types
  406. qdrant < "0.2.0"
  407. qfs
  408. quests
  409. quickterface
  410. rawlink < "2.1"
  411. rawlink-lwt
  412. rdf_json_ld
  413. rdf_lwt
  414. redis-lwt
  415. reparse-lwt
  416. reparse-lwt-unix
  417. resource-pooling
  418. resp
  419. resp-mirage >= "0.10.0"
  420. resp-unix >= "0.10.0"
  421. resto
  422. resto-cohttp-client = "0.4"
  423. resto-cohttp-server = "0.4"
  424. resto-directory = "0.4"
  425. ringo-lwt
  426. river
  427. rock
  428. rpclib-js
  429. rpclib-lwt
  430. SZXX < "4.0.0"
  431. sanddb
  432. scgi
  433. sendmail-lwt
  434. sendmail-mirage
  435. serial
  436. server-reason-react
  437. session-cohttp-lwt
  438. session-cookie-lwt
  439. session-postgresql-lwt
  440. sessions
  441. shared-block-ring
  442. shared-memory-ring-lwt
  443. sherlodoc
  444. sihl < "0.2.0"
  445. slack
  446. slacko
  447. slipshow
  448. smtml >= "0.7.0"
  449. speed
  450. spin < "0.8.0"
  451. spoke
  452. statocaml
  453. stk
  454. stog
  455. swapfs
  456. syguslib-utils
  457. syndic >= "1.4" & < "1.6.0"
  458. tar-mirage
  459. tar-unix
  460. tcpip
  461. telegraml
  462. terminus
  463. testcontainers
  464. testo-lwt
  465. tidy_email
  466. tls >= "0.10.6" & < "0.16.0"
  467. tls-lwt
  468. tls-mirage
  469. tube
  470. tuntap
  471. twirp_cohttp_lwt_unix
  472. uring
  473. uspf
  474. uspf-lwt
  475. uspf-mirage
  476. utcp
  477. utop
  478. uwt
  479. vchan
  480. vchan-unix
  481. vchan-xen
  482. vercel
  483. vhd-format-lwt
  484. vmnet
  485. vue-jsoo < "0.3"
  486. wayland < "2.0"
  487. webauthn
  488. xen-evtchn
  489. xen-evtchn-unix
  490. xen-gnt
  491. xen-gnt-unix
  492. xenstore
  493. xenstore-tool
  494. xenstore_transport
  495. xlsx2csv
  496. yocaml_git
  497. yocaml_unix < "2.0.0"
  498. zarr-lwt
  499. zmq-lwt >= "5.2.1"

Conflicts

None