Gaga about bifs (Was: Complexity Shock Horror II: the Sequel (was Re: MD5 in erlang))

[Robert Virding]

Why is everyone so completely gaga about adding new bifs to do relatively
trivial things? Especially seeing you can already to do it without adding
new stuff. Use erl_scan:string and io_lib:fwrite. I have sent a modified
io_lib to erlang_questions a  couple of times but it hasn't seemed to make
it into the distribution. If Björn sends the sgml manpage I can add it.

My io_lib contained a ~# to write signed based integers and ~b and ~x for
binary and hex bitfields. You usually need these diferent styles of writing
a number.

If someone wants my io_lib I will post it  again.

Robert

----- Original Message -----
From: "Raimo Niskanen" <raimo.niskanen@REDACTED>
To: <erlang-questions@REDACTED>
Sent: Tuesday, April 01, 2003 2:35 PM
Subject: Re: Complexity Shock Horror II: the Sequel (was Re: MD5 in erlang


> Alright then, I will add integer_to_list(Integer, Base) and
> list_to_integer(List, Base) to the module 'erlang', and to the
> documentation for R9C. We will see if they become real BIFs to R9C.
>
> integer(Base), 2 =< Base, Base =< 36.
>
> integer_to_list/2 allows leading '-' or '+' but no prefix. Both
> uppercase or lowercase digits. No internal '_' since integer_to_list/1
> does not allow it, and neither do the compiler. (yet :-)
>
> list_to_integer/2 produces uppercase digits and a leading '-' for
> negative numbers.
>
> / Raimo Niskanen, Erlang/OTP
>
>
>
> integer_to_list(I, Base)
>    when integer(I), integer(Base), Base >= 2, Base =< 1+$Z-$A+10 ->
>      if I < 0 ->
>     [$-|integer_to_list(-I, Base, [])];
>         true ->
>     integer_to_list(I, Base, [])
>      end;
> integer_to_list(I, Base) ->
>      erlang:fault(badarg, [I, Base]).
>
> integer_to_list(I0, Base, R0) ->
>      D = I0 rem Base,
>      I1 = I0 div Base,
>      R1 = if D >= 10 ->
> [D-10+$A|R0];
>     true ->
> [D+$0|R0]
> end,
>      if I1 == 0 ->
>     R1;
>         true ->
>     integer_to_list(I1, Base, R1)
>      end.
>
>
>
> list_to_integer(L, Base)
>    when list(L), integer(Base), Base >= 2, Base =< 1+$Z-$A+10 ->
>      case list_to_integer_sign(L, Base) of
> I when integer(I) ->
>     I;
> Fault ->
>     erlang:fault(Fault, [L,Base])
>      end;
> list_to_integer(L, Base) ->
>      erlang:fault(badarg, [L,Base]).
>
> list_to_integer_sign([$-|[_|_]=L], Base) ->
>      case list_to_integer(L, Base, 0) of
> I when integer(I) ->
>     -I;
> I ->
>     I
>      end;
> list_to_integer_sign([$+|[_|_]=L], Base) ->
>      list_to_integer(L, Base, 0);
> list_to_integer_sign([_|_]=L, Base) ->
>      list_to_integer(L, Base, 0);
> list_to_integer_sign(_, _) ->
>      badarg.
>
> list_to_integer([D|L], Base, I)
>    when integer(D), D >= $0, D =< $9, D < Base+$0 ->
>      list_to_integer(L, Base, I*Base + D-$0);
> list_to_integer([D|L], Base, I)
>    when integer(D), D >= $A, D < Base+$A-10 ->
>      list_to_integer(L, Base, I*Base + D-$A+10);
> list_to_integer([D|L], Base, I)
>    when integer(D), D >= $a, D < Base+$a-10 ->
>      list_to_integer(L, Base, I*Base + D-$a+10);
> list_to_integer([], _, I) ->
>      I;
> list_to_integer(_, _, _) ->
>      badarg.
>
>
>
> Tony Rogvall wrote:
> > Raimo Niskanen wrote:
> >
> >>
> >> Some comments and some problems. Since Erlang supports the
> >> Base#Integer syntax i think that Base in:
> >>     integer_to_list(Integer, Base)
> >> should be 2..16, not atoms.
> >>
> > I just thought it would look nice, but I can buy 2..16 (btw do you know
> > any one using base 13 for output? and since we only alow 2..16 its kind
> > of crippled anyway)
> >
> >
> >> The same for:
> >>     list_to_integer(List, Base)
> >>
> > Oh well.
> >
> >> But what should happen if you call list_to_integer("16#1f", 8), and
> >> how should you specify any base. I guess the answers are: badarg on
> >> the first and list_to_integer("16#1f", undefined) on the second
question.
> >>
> > Like you said, do NOT allow base syntax in the list_to_integer/2 (why
> > should you?) but maybe in list_to_integer/1 (if that does not break
> > anything, it could!)
> >
> >> And to add the prefix in the Right(tm) way is a bit awkward:
> >>     List = case integer_to_list(Integer, 16) of
> >>             [$-|L] -> "-16#"++L;
> >>             L -> "16#"++L
> >>         end
> >
> >
> > My oppinon is that we ignore the prefix stuff completly just to get
> > things on it's way. I myself have never sent any output in base syntax
> > (anyone?).
> >
> > /Tony
>
>