hi! I’ve spent some time thinking about how we can...

# language-proposals

[Alejandro Serrano Mena]

hi! I’ve spent some time thinking about how we can improve is tests in Kotlin by adding some lightweight type refinement on matching; this is what I came up with https://gist.github.com/serras/ee07f36b38756f076d654496a3d2eb61

I would love to know what the community thinks about it; it seems waaay more simple than what Scala does, but it still unlocks quite some power in the type checker

[elizarov]

The “type” smart casts come up from time to in various type-inference use-cases that we study. Your main use-case is a great summary that demonstrates the core of the problem. Nice writeup! However, those kinds of casts are quite non-trivial to actually implement in the compiler. This whole discussion makes sense only if there is a prototype that demonstrates implementation feasibility.
P.S. Please separate out the less controversial part on “type smartcasts” from the new syntax for “existentials” and create a YouTrack issue with your use-case.

[Alejandro Serrano Mena]

thanks for the comments! in fact, I wanted to ask what is the best way to go forward?
• what should I include in the YouTrack issue?
• I’m working on a prototype, where should I link that?

[dmitriy.novozhilov]

• It's ok to copy your description from gist to the issue
• Please mention it in the comments in issue

[dmitriy.novozhilov]

BTW I hope you write your prototype in Frontend IR, not in FE 1.0 (using descriptors and binding context)?

[Alejandro Serrano Mena]

will do!