fsharp
[style-guide] Parameter owner patterns should be consistent with prefix application expressions
Union cases patterns should be consistent with their creation expressions, like this:
let _ = Foo x
let _ = Bar(1, 2)
match s with
| Foo x -> ()
| Bar(1, 2) -> ()
Currently Fantomas adds an extra space in the last pattern, which makes it inconsistent. I propose we should fix this.
@nojaf My initial decision is to agree with this. Please let me know if you think this is wrong or inconsistent.
Sounds reasonable. We currently have two settings that control the spaces before upper/lower case invocations (comment).
These could be re-used. Makes sense.
Hi @dsyme, I've implemented this on Fantomas' side: https://github.com/fsprojects/fantomas/pull/2551 I think we should just go with this, it makes for a more consistent story.
Well, there is no real section on formatting patterns, so maybe we Maybe we need a new section on the level of "Formatting expressions" and "Formatting declarations" called "Formatting patterns"? It could also serve to capture the eventual outcome of https://github.com/fsharp/fslang-design/issues/647.
This is a hill I am willing to die on. I propose we adjust union case construction expressions to mirror the status quo of pattern decomposition instead. The style guide mandates that there be a space between function and tupled arguments (I'd argue this should apply to method invocation too, but that's a different matter). Since class and case constructors can be used like functions, I don't see why the Bar(1, 2) <-> func (1, 2) distinction is desirable.
@kerams While being skeptical about changing such a long standing default behaviour, there's a setting that should help: https://fsprojects.github.io/fantomas/docs/end-users/Configuration.html#fsharp_space_before_uppercase_invocation
I've also tried to share some context in https://github.com/dotnet/fsharp/pull/15847#discussion_r1307322325.
there is also this edge case https://github.com/dotnet/fsharp/issues/15780 for fluent notation that currently prevents method and arguments to be separate.
