From: Oleg <email@example.com> To: firstname.lastname@example.org Subject: [Caml-list] Higher-kinded bounded polymorphism Date: Mon, 13 Sep 2021 21:21:39 +0900 [thread overview] Message-ID: <20210913122139.GA3696@Melchior.localnet> (raw) Abstraction over polymorphic types is something that one comes across from time to time, especially when implementing operations generic over collections, or embedding typed DSLs (particularly in tagless-final style). One immediately learns that OCaml does not have higher-kinded type variables (type variables that range over type constructors like list and array); does not permit type constructors appearing by themselves, without being applied to the right number of arguments; and restricts polymorphic types in other ways (e.g., not allowing them in type constraints of package types). One soon learns that the module system (using functors) is a way to realize higher-kinded polymorphism in OCaml. It takes longer to learn it is not the only way, however. The following web page is written to speed up this learning. It collects what I have learned and rediscovered on this topic, arranged into a single story and with new explanations and attributions (and occasionally, new variations). http://okmij.org/ftp/ML/higher-kind-poly.html One interesting discovery is that some problems that ostensibly require higher-kinded polymorphism really do not. The article comes with the complete accompanying code.
next reply other threads:[~2021-09-13 12:22 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-13 12:21 Oleg [this message] 2021-09-14 17:03 ` Carette, Jacques
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