Provide a way to make fast in-calls into Haskell

Currently, there is no way to call into Haskell without creating a new Haskell thread and running the schedular, which is rather slow. It would be nice to be able to make faster calls into Haskell, even if some state had to be persisted on the C side and passed to the RTS each time.

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 5

added Tbug Trac import labels

Trac metadata

Trac field	Value
Type	Bug → FeatureRequest
Component	Compiler → Runtime System

closed

changed milestone to %8.2.1

We now have a way to call tryPutMVar() from C without creating a new Haskell thread: https://phabricator.haskell.org/rGHC454033b54e2f7eef2354cc9d7ae7e7cba4dff09a

I think this is the best we can do here, so I'll close the ticket. Feel free to re-open if this doesn't work for your use case.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label