Oh, thanks!
So if I wanted to return '(int, charNZ)' instead I'd need some kind of
'praxi' asserting that it's not null?
On Sunday, December 10, 2017 at 8:41:18 AM UTC-6, gmhwxi wrote:
>
> This is the best I could come up with.
>
> Mixing templates with dependent types almost always
> causes problems.
>
> (* ****** ****** *)
> //
> #include
> "share/atspre_staload.hats"
> //
> fn
> length_last
> {l:nat | l > 1 }
> (
> s: string l
> ) : (int, char) = let
> typedef tenv = (int, char)
> var env: tenv = (0,s.head())
> implement
> stream_vt_foreach$fwork<char><tenv>(c,env) = env := (env.0 + 1, c)
> val-~stream_vt_nil() =
> stream_vt_foreach_env<char><tenv>(streamize_string_char(s.tail()), env)
> in
> env
> end
>
> implement
> main0() = let
> val
> tup =
> length_last("abcde")
> in
> println! ("(", tup.0, ", ", tup.1, ")")
> end // end of [main0]
>
>
> On Sun, Dec 10, 2017 at 9:06 AM, aditya siram <[email protected]
> <javascript:>> wrote:
>
>> Hi,
>> I'm trying to pass and mutate a stack allocated tuple in a string
>> processing function:
>>
>> fn length_last
>> {l:nat | l > 1 }
>> (
>> s: string l
>> ): (int, char) =
>> let
>> var env = (0,s.head())
>> implement stream_vt_foreach$fwork<charNZ><(int,charNZ)>(c,env) =
>> env := (env.0 + 1, c)
>> val _ = stream_vt_foreach_env(
>> streamize_string_char(s.tail()),
>> env
>> )
>> in
>> env
>> end
>>
>> The stack allocated 'env' should finally have the length of the string
>> and the last character after 'stream_vt_foreach_env' is run. Instead I get
>> compile errors like:
>> length_last.dats:15:13: the dynamic expression should be a left-value
>> but it is not.
>>
>> length_last.dats:11:3: the linear dynamic variable [env$view$5548(-1)] is
>> preserved but with an incompatible type.
>>
>> length_last.dats:11:3: mismatch of static terms (tyleq):
>>
>> The actual term is: S2Etop(knd=0; [1])
>> [1]: S2EVar(5260)
>> The needed term is: S2Etyrec(flt0; npf=-1; 0=S2Etop(knd=0; S2Etop(knd=0;
>> [1])), 1=S2Etop(knd=0; S2Etop(knd=0; [2])))
>> [1]: g1int_int_t0ype(int_kind, 0)
>> [2]: charNZ
>>
>> length_last.dats:11:3: mismatch of static terms (tyleq):
>>
>> The actual term is: S2Eat(S2Etop(knd=0; [1]); [2])
>> [1]: S2EVar(5260)
>> [2]: env
>> The needed term is: S2Eat(S2Etyrec(flt0; npf=-1; 0=S2Etop(knd=0; S2Etop(
>> knd=0; [1])), 1=S2Etop(knd=0; S2Etop(knd=0; [2]))); [3])
>> [1]: g1int_int_t0ype(int_kind, 0)
>> [2]: charNZ
>> [3]: env
>> patsopt(TRANS3): there are [2] errors in total.
>> exit(ATS): uncaught exception:
>> _2home_2deech_2Downloads_2ATS_2ATS2_2src_2pats_error_2esats__FatalErrorExn
>> (1025)
>>
>> Is the problem that I'm passing a stack allocated tuple as the
>> environment?
>>
>> Thanks!
>>
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>>
>
>
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