Re: compiler types: records / collections interaction

[Kon Lovett]

> On Feb 9, 2024, at 11:59 AM, Al <frm.ml@mailgw.com> wrote:
> 
> Suppose I need a record of a record type myrec, and collections (vectors-of, 
> lists-of and hash-tables) with values myrec.

(define-type myrec (struct myrec))
(define-type myrec-vec (vector-of myrec))

(: myrv-ref (myrec-vec fixnum —> myrec)
(define myrv-ref vector-ref)

> 
> 
> What combination of
> 
> * define-record-type (srfi-9, srfi-99, chicken define-record, whatever) and
> 
> * (declare type ...)
> 
> can I use to inform the compiler that (for collections of myrec) vector-ref 
> returns myrec's (likewise list car/cdr, hash-table-ref)? And that it needs 
> not emit any instance-type-checking code for objects extracted from such 
> collections?
> 
> 
> Furthermore, how can I see what the compiler thinks of a given identifier? 
> I've used 'csc -ot' but it only emits types for some identifiers. Maybe it 
> inlines others, I don't really know.
> 
> 
> Separately, how can I tell the compiler that fields in these records have 
> certain types? Add type declarations for the implicitly-defined per-field 
> accessors and mutators?

(import typed-records)
(define-record myrec (a : float) (b : symbol))

does this for you

(: make-myrec (float symbol -> (struct myrec)))
(: myrec? (* -> boolean : (struct myrec)))
(: myrec-a ((struct myrec) -> float))
(: myrec-b ((struct myrec) -> symbol))

> 
> 
> I've tried unwrapping collections of myrec, and also myrec fields, and it 
> seems to make a huge difference in the speed of compiled code. Presumably 
> because I don't know how to tell the compiler to omit type checking in "safe" 
> cases. I know I could use some of the more aggressive optimization levels, 
> but I don't really want to compile unsafe code everywhere, just where  I'm 
> using the correct types.
> 
> 
> Thanks,
> 
> Al
> 
>