Regex seems to yield different results with Fable

[lfr]

Repro code

Regex.IsMatch("\\p{C}", "a\nb") // false (FABLE)
Regex.IsMatch("\\p{C}", "a\nb") // true (non-FABLE)

Related information

• Fable version: 2.13.0
• Windows

[lfr]

From F# fiddle:

[alfonsogarciacaro]

How are you evaluating the F# fiddle? If I try this in F# interactive I get false too.

[lfr]

Ok, it must be a bug with .NET 5 then, I evaluated it with dotnetfiddle.net that's probably still running on an earlier version.

[inosik]

.NET 5 behaves differently on Windows in regards to the previous versions, see dotnet/runtime#43736. This probably affects Regex as well.

Also, note that Fable translates to JavaScript and isn't a fully fledged .NET runtime for the browser. So this is actually a mismatch between .NET and the browser.

[alfonsogarciacaro]

Thanks @inosik ! Yes, sorry. Forgot to say that, as mention in the docs, regex in Fable behave as if you're using the RegexOptions.ECMAScript flag (no named groups for example) so it's better to use it explicitly for a proper comparison.