Separator between member and type annotation interpreted as operator

[cartermp]

Given the following:

type IFoo<'T> =
    abstract member Bar<'T>: name: string -> unit

Expected:

Compiles.

Actual:

Compiler error.

This construct is deprecated: ':' is not permitted as a character in operator names and is reserved for future use

Workaround:

Put a space after the >:

type IFoo<'T> =
    abstract member Bar<'T> : name: string -> unit

Thanks to @jaredpar for pointing this out

Info

Latest F# compiler in VS Preview

[abelbraaksma]

I think in a way this is similar to static member constraints, similar because I think the compiler misinterprets >: as an operator, just as here:

let inline internal getValue<^a when ^a : (member Value : string option)> value =
    ( ^a : (member Value : string option)(value))

This raises "Unexpected infix operator in pattern". Or simpler, same error:

let inline internal getValue<^a>(value: ^a) = value

I was quite sure I reported that some years ago, but I can't find it back.

[abelbraaksma]

From the linked issue, there’s an open language suggestion that fixes this, here’s the rfc: https://github.com/fsharp/fslang-design/blob/main/RFCs/FS-1083-srtp-type-no-whitespace.md

[edgarfgp]

@abelbraaksma Just tried with version 7 and this still happens. |So looks like the SRTP whitespace relaxation did not help here :(

[abelbraaksma]

Thanks for trying it out. Fantomas often autocorrects such code, but it’s better if this could still be completely fixed, I think the language spec allows it.