Re: does a safer language mean it is slower to run?

[robin vowels <robin51@dodo.com.au>]

On Thursday, 8 June 2023 at 16:57:17 UTC+10, Niklas Holsti wrote:
> On 2023-06-08 6:55, Nasser M. Abbasi wrote: 
> > Some folks in this thread 
> > 
> > https://discourse.julialang.org/t/comparison-of-rust-to-julia-for-scientific-computing/78508 
> > 
> > "I’m not an expert, but my feeling is that Rust is a “safer” language, 
> > which to me means it must be slower." 
> > 
> > etc.. 
> > 
> > Some in that thread seem to argue that a safer language 
> > will/could be slower than otherwise. 
> > 
> > Since Ada is known to be one of the safest languages, 
> > do others here feel there is any truth to this? 
> > 
> > I thought that by having more type information in the language, 
> > the compile will be able to make more optimizations (because it 
> > know more), and hence the generated code should actually be 
> > faster, not slower with a language that is less safe? 
> > 
> > I am not a compiler expert but what do others here think?
.
> If a language needs run-time checks to ensure safety, those checks 
> usually take some time, making for slower execution. 
.
Some language features need run-time checks.  These checks cannot be
carried out at compile time.
.
PL/I has some features that require run-time checks.  When the computer
hardware has certain facilities, that support does not take extra execution  time.
For example, floating-point overflow and integer overflow are detected by the
hardware on the IBM S/360 and subsequent machines including up to the latest
System z.  Such detections cause an interrupt that can be handled by the PL/I
program.  On the PC, integer overflow can cause an interrupt.
.
> If a language has a type system and compilation-time (legality) rules 
> such that the compiler can prove that some run-time checks are not 
> needed, that reduces or eliminates the slow-down. This is the case for Ada. 
.
Range is not one of them.
.
> The effect of type information on optimization is harder (at least for 
> me) to understand. If the type information lets the compiler assume that 
> some objects are not aliased, that can help optimization because more 
> computation can be done in registers alone, without using main memory. 
> This applies to Ada, but also applies to standard C, for example, 
> although some people use non-standard C features (compiler options) to 
> negate this. 
> 
> However, when comparing the "speed" of two languages and their two 
> implementations I think that the implementations usually matter more 
> than the languages.