Current limitations

Limitation	Why	Workaround
Record update syntax `...record`	Parser accepts it; runtime throws.	Construct a new record explicitly with the fields you want to change.
`extern` calls in JIT mode	JIT has no Salesforce runtime.	Run these code paths with `vertex run --sf --org <alias>` or from a deployed Apex test.
SOQL in Vertex source	SOQL is not yet part of the language.	Wrap the specific queries you need with `extern fn` around `Database.query` / `queryWithBindings`.
`while` and `do`/`while` statements	Intentional: iteration is `for..in`, recursion, or combinators.	Use `for..in`, `List.fold`, or recursion.
Mutating methods on collections	All collection operations are pure.	Rebind: `let xs = xs.add(item)`.
`null` in user code	Intentional: absence is `Option<T>`.	Use `Option<T>` with `Some` / `None`.
`throw` / `try` / `catch` in user code	Intentional: failure is `Result<T, E>`.	Return `Result<T, E>` and propagate with `?`.
Class inheritance	Intentional: composition over inheritance.	Model shared behaviour with interfaces; share implementation via module-level functions.
Static methods on types	Intentional: module-level `fn` only.	Put “static” helpers at module level; readers see them as regular functions.
Parameterised tests	Not yet supported.	Loop inside an `@Test` function over a list of cases.
Before/after hooks in tests	Not yet supported.	Factor shared setup into a helper function called at the top of each test.
Formatter	Not yet available.	Follow the examples in the tour for idiomatic style.
Raw string literals	Not yet supported.	Use explicit escape sequences.
VS Code / JetBrains extensions	Not yet available.	Any LSP-capable editor can drive `vertex lsp`. Zed has a purpose-built extension.

When a limitation bites

If you hit a limitation in a real project, file an issue at vertex-run/vertex with a minimal reproducing example. The list above is curated; a “thing I tried and it didn’t work” that is not listed is almost always a bug worth reporting.