Define "abstraction pattern" and "reabstraction" in the Lexicon. #6493
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Does this look reasonable, @jrose-apple or @rjmccall? Hard to judge what level of depth to get into defining these terms here. |
| var value: (T) -> U // Bar.value has abstraction pattern <T, U> (T)->U | ||
| } | ||
| struct Bas { | ||
| var value: (Int) -> String // Bas.value has abstraction pattern |
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Didn't you forget the pattern here?
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Indeed, thanks @JaSpa!
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| @@ -23,6 +23,40 @@ source code, tests, and commit messages. See also the `LLVM lexicon`_. | |||
| generic context. Sometimes known as a "rigid type variable" in formal | |||
| CS literature. Directly stores its conforming protocols and nested | |||
| archetypes, if any. | |||
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| abstraction pattern | |||
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Alphabetical, please. :-)
| direct register-based calling convention. The compiler transparently | ||
| introduces `reabstraction` conversions when a value is used with a | ||
| different abstraction pattern. (This is where the infamous "reabstraction | ||
| thunk helpers" you sometimes see in Swift backtraces come from.) |
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Nitpick: I think this is the right level of detail but the wrong audience. Lexicon.rst is aimed at contributors to swiftc rather than users.
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I'm not sure what you're referring to exactly. Compiler developers do also have to look at backtraces sometimes…
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Fair enough. I guess I was just going for a "dictionary" tone rather than an "instructing" tone; there isn't an implied "you" in any of the other terms. Not that important.
| @@ -235,6 +269,10 @@ source code, tests, and commit messages. See also the `LLVM lexicon`_. | |||
| IR generation. | |||
| See `mandatory passes <mandatory passes / mandatory optimizations>`. | |||
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| reabstraction | |||
| An implicit representation change that occurs when a value is used with | |||
| a different `abstraction pattern` from its current representation. | |||
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Ah, do we not consider things reabstractions unless they change a representation like this? (e.g. Optional to non-Optional in covariant overrides)
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Interesting question. We do use the "abstraction pattern" concept to govern method representations, so variance-related thunks could indeed be considered reabstractions.
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@jrose-apple Revised to fix alphabetical order and remove wanton second-person pronouns. |
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