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F# Compiler Community Session - Typechecker - An Online Chat with Don, Vlad and Community
Hello everyone, this is an announcement for our 6th compiler community session.
What: F# Typechecker - An Online Chat with Don, Vlad and the community.
When: Tuesday 9th of March 2021, 7pm GMT (UK time), 8pm CET (Central European Standard Time), 11am PT (check your local time here).
Topics for our sixth session:
F# type checker:
- Type inference.
- SRTPs and Witness passing.
- Mutually recursive definitions.
Previous sessions can be found here: 1, 2, 3, 4 5, or on F# Software Foundation YouTube channel
Update: Recording is available.
(I'm posting this in advance so that I can simply link to it later.)
There was a question in the FSSF slack yesterday:
I posted a problem in the beginners thread yesterday, which Dave Shaw has reduced to this (thank you):
type R = { F: string seq -> unit }
let f (xs : string seq) = ()
// ex. 1
f [] //Works
// ex. 2
let r = { F = f }
r.F [] //< This one doesn't compile
// ex. 3
let rf = r.F
rf [] //Also works
Instead of workarounds (like "put in a seq") I would like to understand, why I can pass a list as seq in the one way, but not the other. Any hints?
Writing ([] :> string seq) allows example 2 to work, so while this is not a major usability issue, it may be worth discussing how/why F# behaves this way.
Teams meeting link: https://teams.microsoft.com/l/meetup-join/19%3ameeting_NjA3Njc1YWEtN2Y1ZS00ZGQxLWJmY2YtZTgwZTliZTIxOWE2%40thread.v2/0?context=%7b%22Tid%22%3a%2272f988bf-86f1-41af-91ab-2d7cd011db47%22%2c%22Oid%22%3a%2297f10a8e-3843-4db7-8ef7-f449e82693d7%22%7d
@vzarytovskii Since we did not get to SRTP and witness passing or other non-inference-related aspects of typechecking, is there a possibility of it being discussed as part of a future session? (Naturally, much time could be spent on the typechecker alone, so it's understandable if a future session will be about other aspects instead!)
Thanks for hosting these events, by the way.
@vzarytovskii Hi, are you planning to post this most recent session to YouTube?
@vzarytovskii Hi, are you planning to post this most recent session to YouTube?
Hey, yeah, sorry, I was preoccupied with some other work-related stuff. I've downloaded the video already, need to edit it a bit and upload. Hopefully will get to it tomorrow.
