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Update polymorphic-table-types.md

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docs/polymorphic-table-types.md
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@ -83,12 +83,13 @@ local a = components[A]
-- { [Factory<any>]: any? }[Factory<'Bar'>] ==> any? -- { [Factory<any>]: any? }[Factory<'Bar'>] ==> any?
local b = components[B] local b = components[B]
``` ```
We've lost our type information of `a` and `b` in the last table step!
- "Why not use a getter?"
- Mentioned before, API bloat or performance concerns, getting components from this table usually happens during iterations and thousands of times a frame.
- "Why not implement better metamethod inference?" We've lost our type information of `a` and `b` in the last table step!
- The `components` table guarantees users may define their own metatables. Metatables are not an elegant, reliable, or wholly-acceptable solution to this lack of types. However better inference is always a good thing! This is a great idea for a *different* RFC.
- "Why not use a getter?"
- Mentioned before, API bloat or performance concerns, getting components from this table usually happens during iterations and thousands of times a frame.
- "Why not implement better metamethod inference?"
- The `components` table guarantees users may define their own metatables. Metatables are not an elegant, reliable, or wholly-acceptable solution to this lack of types. However better inference is always a good thing! This is a great idea for a _different_ RFC.
## Design ## Design
@ -131,6 +132,7 @@ We believe that this implementation is a natural step in the direction towards a
`function` $\cong$ `table` `function` $\cong$ `table`
### Inferability ### Inferability
In order for T to be inferable, it must appear in the argument of a function or key of table. If it is not present, the mapped type is left as a free-type, denoted `a`, `b`, ... In order for T to be inferable, it must appear in the argument of a function or key of table. If it is not present, the mapped type is left as a free-type, denoted `a`, `b`, ...
```lua ```lua
@ -148,6 +150,7 @@ In order for T to be inferable, it must appear in the argument of a function or
``` ```
### Indexers ### Indexers
At the time of this RFC, table types only support a single indexer excluding string keys. This is as complex as a table may be: At the time of this RFC, table types only support a single indexer excluding string keys. This is as complex as a table may be:
```lua ```lua