Improved Signature Help in Merlin • Backstage OCaml

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Merlin's signature-help feature, which displays function signatures and highlights the active parameter as you type, has received several improvements:

Parameter-only display: Signature help now only appears on function parameters, no longer on the function name itself.
No more parameter looping: After the last parameter, the highlight no longer wraps back to the first one.
Better context support: Signature help now activates within let .. in bindings even before the in keyword is written.
Optional parameter detection: Optional parameters are now correctly detected and highlighted when the user starts writing one.

Some of these improvements are already available in the latest Merlin and ocaml-lsp releases, with the rest coming in upcoming versions.