Poly/ML October 2025

polyml@lists.polyml.org

11 participants
2 discussions

ML Basis
by vqn 31 Oct '25

31 Oct '25

Hello, Over the past few months, I have been working on an implementation of the ML Basis system for Poly/ML. It supports the complete mlb spec and is available both as a library and a cli tool: https://github.com/vqns/polymlb On a side note, I have been trying to implement incremental compilation by caching compiled .mlb files (i.e compiler namespaces) and exporting and reimporting them through {save,load}ModuleBasic. I have however been running into the issue that exporting each .mlb to a different on-disk module causes opaque types mismatch when reimporting them. What would be the reason for that? I have managed to work around it by exporting everything to the same file, but that result in a fairly large cache, e.g ~45mb for smlfmt (1.2mb executable, 15k loc). I suppose the reason for that is that I export the basis library as well, but I'm not sure there is a solution for that.

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tuple indexing: 0-based or 1-based?
by Gabriel Scherer 28 Oct '25

28 Oct '25

Dear SML people, There is an OCaml feature proposal by Alistair O'Brien that would finally introduce tuple indexing in OCaml -- we currently have only whole-tuple pattern matching: RFC: https://github.com/johnyob/ocaml-RFCs/blob/tuple-projections/rfcs/tuple_pro… discussion: https://github.com/ocaml/RFCs/pull/57 Of course this raises the Very Important Question of whether indexing should be 0-based or 1-based. The argument in favor of 0-based is that it is what we use for arrays, so more consistent, standard in most programming languages. The argument in favor of 1-based is that it is arguably more intuitive (but the inconsistency with arrays weakens this claim noticeably), and that SML uses it. Question: you have a lot more experience using tuple indexing. In your opinion, if this was to be decided again for a new system (no backward-compatibility concerns), would you still recommend using 1-based indices, or would you be more in favor of 0-based indices? P.S.: You may be amused to learn that OCaml recently introduced "labeled tuples" (looking like `(x:1, y:2)` in expressions and `(x:int * y:int)` in types), which are basically a restricted version of SML structural records -- type inference does not try very hard and requires an annotation in practice. P.P.S: Is there still a mailing-list for the SML/NJ crowd? All I could find were github discussions (https://github.com/orgs/smlnj/discussions) and an invite-only Zulip.

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Poly/ML October 2025