> Almost none of the languages mentioned are "formally specified"
They all have written specs. Many of them even have these specs standardized, see ANSI INCITS 226-1994, ISO/IEC 16262 and ISO/IEC 23270:2018.
> most of them are hardly fast either
It’s borderline impossible to be fast compared to C or C++. By that statement I meant 2 things.
(1) They’re likely to be much faster compared to whatever ad-hoc equivalent is doable within reasonable budget. People spent tons of resources improving these runtimes and their JITs, it’s very expensive to do something comparable.
(2) On modern hardware, their performance is now adequate for many practical uses. This is true even for resource-constrained applications like videogames or embedded/mobile software, which were overwhelmingly dominated by C or C++ couple decades ago.
They all have written specs. Many of them even have these specs standardized, see ANSI INCITS 226-1994, ISO/IEC 16262 and ISO/IEC 23270:2018.
> most of them are hardly fast either
It’s borderline impossible to be fast compared to C or C++. By that statement I meant 2 things.
(1) They’re likely to be much faster compared to whatever ad-hoc equivalent is doable within reasonable budget. People spent tons of resources improving these runtimes and their JITs, it’s very expensive to do something comparable.
(2) On modern hardware, their performance is now adequate for many practical uses. This is true even for resource-constrained applications like videogames or embedded/mobile software, which were overwhelmingly dominated by C or C++ couple decades ago.