Add Extract to let binding and Extract to literal refactorings

[xperiandri]

Offers Ctrl+. on a selected expression to bind it to a let in front of the statement that uses it, or, for a constant in a module-level declaration, to a [<Literal>] above that declaration. A caret inside a constant offers the literal; a caret in the fun … -> header of a parenthesized lambda extracts the lambda.

The value is computed at the start of the enclosing statement, so it can run earlier than where it was written, as with C#'s Introduce Local. The selection must match a whole expression; nothing is offered inside quotations, interpolation holes, while conditions or when guards.

🤖 Generated with Claude Code

[github-actions]

❗ Release notes required

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✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
`vsintegration/src`	docs/release-notes/.VisualStudio/18.vNext.md

[xperiandri]

Suggested change

	|> List.ofSeq
	|> Seq.toList

[github-actions]

🔍 Tooling Safety Check — Affects-Design-Time
Affects-Design-Time: Modifies Visual Studio code executed while projects are open.

Generated by PR Tooling Safety Check · gpt56 1.8M · ◷

[T-Gro]

🤖🕵️ Please shorten the description using this guidance. Focus on the problem and why the change is needed, in simplified technical English. Leave the implementation inventory to the Files tab and retain necessary caveats.

[xperiandri]

Covered cases

Offered

• An expression inside a statement is bound on the line before it: selecting w * h + 1 in printfn "%d" (w * h + 1) → let extracted = w * h + 1 + printfn "%d" (extracted); selecting (w * h + 1) removes the parentheses: printfn "%d" extracted
• Method-call parentheses stay: selecting (1 + 2) in sb.Append(1 + 2) → sb.Append(extracted)
• A multi-line pipeline on the right of let total = is bound in front of that let as let extracted = + the indented pipeline, and let total = then holds extracted; also when whole lines are selected with their indentation and line break
• A body sharing its line with -> moves to its own lines: | Some v -> v * 2 + offset and (fun x -> x + 1) become -> followed by let extracted = … and extracted
• A right-hand side on the = line keeps its trailing comment: let r = compute a b // slow → let extracted = compute a b + extracted // slow
• Inside a computation expression the binding goes before the statement: return parse raw |> List.length } → let extracted = parse raw |> List.length + return extracted }
• The name avoids existing identifiers: extracted1 when extracted is already used
• CRLF line endings are kept
• Lines inside a multi-line triple-quoted string (String.Format("""Hello … {0}""", name)) are not re-indented
• Extract to literal inserts a declaration in front of the module-level let: "Hello %s" → [<Literal>] let ExtractedConstant = "Hello %s"; a negative number g -1 → let ExtractedConstant = -1
• Which actions appear: for 42 in a module let, both "Extract to let binding" and "Extract to literal"; only the let binding for 42 in member _.M() = 42 and for x + 1
• With no selection, a caret at the start of, inside (llo %s) or at the end of "Hello %s" gives the literal extraction; a caret inside 42 offers only the literal
• With no selection, a caret on fun, the parameter, the arrow or right after it in xs |> List.map (fun x -> x + 1) extracts the whole lambda: let extracted = fun x -> x + 1 + xs |> List.map extracted (only the let binding is offered)

Not offered

• With no selection, a caret in the lambda body (x + 1), + 1)), on the opening (fun parenthesis, or on a lambda without parentheses let f = fun x -> x + 1
• With no selection, a caret on a non-constant g x, on 42 in member _.M() = 42, or on 1 in the interpolation $"{a + 1}"
• A selection that is not a whole expression: w * h + in w * h + 1, or 2 + 3 in 1 + 2 + 3
• A then branch sharing its line with else: x + 1 in if c then x + 1 else y
• Selections inside a while condition i < n, a when guard v > 0, an interpolation $"{a + b}", or the right operand of &&: s.Length > 0
• return id in a computation expression, the argument tuple a, b of sb.Insert(a, b), or a lone identifier x in x.ToString() + ""
• An empty selection outside any constant or parenthesized lambda (let f x = x + 1)