alt Hacker NewsKotlin heavily uses the inline keyword basically everywhere, to get rid of lamdba overhead for functions like map. Basically every stdlib and 3rd part library function that takes a lamdba is inlined.
In general it's a performance benefit and I never heard of performance problems like this. I wonder if combined with Scala's infamous macro system and libraries like quicklens it can generate huge expressions which create this problem.
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gavinray • last Sunday at 7:54 PM
The killer is specifically the inlining of macros -- which Kotlin lacks.
And not all macros, but just the ones which expand to massive expressions
Think template expressions in C++ or proc macros in Rust
This is one example why being a guest language isn't optimal.
They should have made use of JVM bytecodes that allow to optimize lambdas away and make JIT aware of them, via invokedynamic and MethodHandle optimizations.
Naturally they cannot rely on them being there, because Kotlin also needs to target ART, JS runtimes, WebAssembly and its own native version.