Allow free vars in types for coercion. #6828
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
cristianoc
added a commit
that referenced
this pull request
Jun 25, 2024
There are two forms of type coercion: 1 `e: t0 :> t` 2 `e :> t` The first form was never supported in .res syntax, and is now removed from parsed and typed tree. That said, coercion 1 is the only one that ever supported coercion with free variables. So this is subject to more investigation. See #6828
|
So, this enables you to use free variables when coercing...? I guess I don't fully understand the change. |
This just disables the check for free variables. |
|
I wonder what types of issues it could cause.. |
|
Tried to run all tests in the ocaml repo, and they work after this change. Here's a bunch of new things that type check: module NoFreeVars = {
type t = private int
let f = (x: t) => (x :> int)
let g = (y: t) => ()
let h = x => (g(x), (x :> int))
let h2 = x => ((x :> int), g(x))
}
module WithTypeArg = {
type t<'a> = private int
let f = (x: t<_>) => (x :> int)
}
module FunctionType = {
type t = private int
let f = _ => (Obj.magic(3) : t)
let _ = f :> (_ => int)
}
module Contravariant = {
type t = private int
let f1 = (_:int) => ()
let _ = f1 :> (t => unit)
let f2 = (_:int, _) => ()
let _ = f2 :> ((t, _) => unit)
}
module Totallypoly = {
let f = x => (x :> int)
let idint = (x:int) => x
let _ = f == idint
} |
cristianoc
force-pushed
the
coercion_free_vars
branch
from
915cf36 to
16ae754
Compare
cristianoc
added a commit
that referenced
this pull request
Jul 2, 2024
There are two forms of type coercion: 1 `e: t0 :> t` 2 `e :> t` The first form was never supported in .res syntax, and is now removed from parsed and typed tree. That said, coercion 1 is the only one that ever supported coercion with free variables. So this is subject to more investigation. See #6828
cristianoc
added a commit
that referenced
this pull request
Jul 2, 2024
…6829) * Remove coercion with 2 types, which is only supported in ml syntax. There are two forms of type coercion: 1 `e: t0 :> t` 2 `e :> t` The first form was never supported in .res syntax, and is now removed from parsed and typed tree. That said, coercion 1 is the only one that ever supported coercion with free variables. So this is subject to more investigation. See #6828 * Cleanup and indent. * Make Texp_coerce compatible with old runtime representation. By adding a unit argument to the payload.
See #6821 Free variables are not allowed in coercion, and if that happens, simple unification is performed without ever attempting coercion. This seems to go back a very long time. There's probably a good reason why free vars were not allowed. At the same time, there are no objects/classes supported in the language anymore, so it's not clear how those reasons would adapt. This just marks the place where one could investigate.
cristianoc
force-pushed
the
coercion_free_vars
branch
from
3312be7 to
7a4b87f
Compare
zth
approved these changes
Jul 2, 2024
cristianoc
changed the title
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
See #6821
Free variables are not allowed in coercion, and if that happens, simple unification is performed without ever attempting coercion. This seems to go back a very long time.
There's probably a good reason why free vars were not allowed. At the same time, there are no objects/classes supported in the language anymore, so it's not clear how those reasons would adapt.
This just marks the place where one could investigate.