Updates `Environment` to store all feature flags on a single `config` object. We
now also define an object with all the default config values, and use this to
populate defaults for any missing values in the user-provided config.
InferReferenceEffects uses object identity to merge states, which breaks when we
create a new object to model `undefined`.
Two value objects representing `undefined` are not equal due to referential
equality.
Instead, let's use a singleton to represent `undefined` value.
Adds a new type for representing context values, which is transitive. So
`useContext(a).b.c` also gets inferred as a context type. This allows us to
refine our inference, and allow passing callbacks that modify context where a
"frozen" lambda is exepcted.
Object methods are lowered to functions and added to ObjectExpression. The
codegen is interesting because we shouldn't emit code that lowers the object
method into a separate statement and then stores it into an object expression.
An shorthand object method has different semantics than an object method using
the function syntax, so we need to preserve the shorthand object method syntax
in the generated code.
To do this, we don't immediately generate an AST node for the ObjectMethod but
instead store it in a side table during codegen. Only when emitting code for an
ObjectExpression, we lookup this side table and emit the object method inline in
the body.
Replaces the use of `NextIterableOf` in for-in with a new `NextPropertyOf`
instruction. The key distinction is `for-of` invokes an arbitrary iterator,
which means a) each iteration may mutate the collection being iterated and b)
the returned value may be mutable. However, `for-in` invokes a language-level
mechanism to iterate: simply iterating alone _cannot_ modify the collection, and
the returned value is known to be a primitive.
Sorry about the thrash in advance! This removes the top level `forget` directory
which adds unnecessary nesting to our repo
Hopefully everything still works
Joe Savona
Sathya Gunasekaran
lauren