My current, not so successful try is to define result_vt:
datavtype result_vt (av: view, a:t@ype+, bv: view, b:t@ype+) =
| Success_vt(av,a, bv, b) of (av | a)
| Failure_vt(av,a, bv, b) of (bv | b)
and function's ftype:
fn
recvfrom
{l: addr} {n: pos}
( buf_pf: array_v(char?, l, n)
| socket_fd: int
, buf: ptr l
, sz: size_t n
, flags: int
, src_addr: &sockaddr_in_struct?
, addr_sz: &size_t
): [m:pos | m <= n] result_vt( (array_v(char,l,m), array_v(char?,l+m,
n-m)), (sockaddr_in_struct, size_t m), array_v(char?,l,n), void) =
let
val ret = g1ofg0( $extfcall(ssize_t, "recvfrom", socket_fd, buf, sz,
flags, addr@src_addr, addr@addr_sz))
in
if ret < 1
then Failure_vt( buf_pf | ())
else Success_vt( (answer_pf, rest_buf_pf) | (src_addr, ret) (*complains
on this line *) ) where {
extern praxi unnil{v:viewt0ype} ( p: &v? >> v): void
prval () = unnil(src_addr)
val (answer_pf, rest_buf_pf) = array_v_split( buf_pf)
}
end
but compiler is not happy with it, giving me errors:
error(3): the dynamic expression cannot be assigned the type [S2EVar(5259)].
error(3): mismatch of sorts in unification:
The sort of variable is: S2RTbas(S2RTBASimp(9; t@ype+))
The sort of solution is: S2RTbas(S2RTBASimp(3; viewt0ype))
error(3): mismatch of static terms (tyleq):
The actual term is: S2Etyrec(flt0; npf=-1; 0=S2EVar(5253),
1=S2Eapp(S2Ecst(g1int_int_t0ype); S2Eextkind(atstype_ssize),
S2Evar(i$8638$8639(14396))))
The needed term is: S2EVar(5259)
пт, 10 июл. 2020 г. в 12:47, [email protected] <[email protected]>:
>
> Hi again :)
>
> I have function
>
> fn
> recvfrom
> {l: addr} {n: pos}
> ( buf_pf: array_v(char?, l, n)
> | socket_fd: int
> , buf: ptr l
> , sz: size_t n
> , flags: int
> , src_addr: &sockaddr_in_struct?
> , addr_sz: &size_t
> ): [m:int] ssize_t int
>
> I want to change it's return type, such that in case of success, it should
> split buf_pf on 2 arrays: initialized and unintialized one and src_addr to
> became initialized.
> In case of failure, I want to return buf_pf and src_addr of the same view
> (uninitialized)
>
> How can I do it properly?
>
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