I think both are very close.

I would say that f is faster, because r.a is loaded only once. However,
this can increase register pressure...

I would say to use whichever is more easy to use a a given context, and
to tune specifically the code if this is the bottleneck: this is very
unlikely to be the performance bottleneck, and there won't be a big
performance improvement anyway...


-- 
JH

Le 15/09/2013 12:30, José Romildo Malaquias a écrit :
> Hello.
> 
> OCaml offers at least two ways of accessing a record field: using the
> dot notation, and doing pattern matching.
> 
> Does one of them deliver better performance than the other?
> 
> This may be relevant when a field is accessed multiple times.
> 
> For instance:
> 
>    type trec = { a : int; mutable b: int }
> 
>    let f {a;b} = a * a + b
> 
>    let g r = r.a * r.a + r.b
> 
> Which one would be preferred in this case: f or g?
> 
> Romildo
>