Hugo Estrada's House of Wonder

Yeah, I also wanted to start a political party. And an international political party for that since I am already making one. It is the the International Love Party, where people who are moved by love can join together, enhance their love for humanity and maybe even do something!

I will put a link to its blog soon. Hopefully the store will get up quickly as well.

This stormy weekend I got to make a number of nice silly goals. I built a snow maze in the driveway, I made another igloo, the biggest one that I have made, actually, and I built a sled area for the kids to go down our driveway. I used their sleds to snowboard down it. It was fun.

I did this in the last month over a weekend. We hiked for 6 hours in Great Falls, MD. We hiked over the park in the trails, and then we visited the vistor's center and saw this great little gate keeper museum there. Then we saw part of the falls. We were going to go to the Billy Goat Trail Section A, but then I saw the entry to Olmstead Island, which I haven't been to at all, and we went there first. It was great, and my daughter really loved the island.

Then we went to hike on the Billy Goat Trail Section A. We got to finish half of it since it got dark. We had to use the emergency trail exit. Then we hiked in the canal towpath in the darkness until we got to the car. It was really nice. :)

Okay, this is something I was going to blog about a month ago, but then the January storm hit and derailed that.

So, these are the first 22 exercises of the 99 Prolog Problems. I am doing them in Erlang. I know, I know, this is super cryptic by naming the functions after its problem number rather than by nice descriptive problems, but I was taking the easy way out; I just wanted to do them pretty quickly rather than show them off as an exercise on proper programming technique.

For what it is worth, here they are:

-module(p99a).
-export([a1/1, a2/1, a3/2, a4/1, a4b/1, a5/1,
a6/1, a7/1, a7b/1, a8/1, a8b/1, a9/1, a10/1,
a11/1, a12/1, a13/1, a14/1, a15/2,
a16/2, a17/2, a18/3, a19/2, a20/2,
a21/3, a22/2]).

%Find the last element of a list.
a1([], Result) -> Result;
a1([H|T], _) -> a1(T,H).

a1(List) -> a1(List, "Not a list").

%Find the last but one element of a list.
a2([_|[]], Result) -> Result;
a2([H|T], _) -> a2(T,H).

a2(List) -> a2(List, "not a list").

%Find the K'th element
a3([], _, _) -> {error, "out of range"};
a3([H|T], Nth, Index) ->
if Index == Nth -> H;
true -> a3(T, Nth, Index + 1)
end.

a3(List, Nth) -> a3(List, Nth, 1).

%Find the number of elements of a list.
a4([], Result) -> Result;
a4([_|T], Result) -> a4(T, Result + 1).

a4(L) -> a4(L, 0).

a4b([]) -> 0;
a4b([_|T]) -> a4b(T) + 1.

%Reverse a list.
a5([], R) -> R;
a5([H|T], R) -> a5(T, [H|R]).

a5(L) -> a5(L, []).

%Find out whether a list is a palindrome.
equal([], []) -> true;
equal([H|T], [H1|T1]) ->
if H == H1 -> equal(T, T1);
true -> false
end.

a6(L) -> equal(L, a5(L)).

%Flatten a nested list structure.
% a7 is concat in the O'Reilly Erlang book
% a7b is flatten per se
strip([], R) -> a5(R);
strip([H|T], R) -> strip(T, [H|R]).

a7([], R) -> R;
a7([H|T], R) -> a7(T, strip(H, R)).

a7(L) -> a7(L, []).

a7b([],R) -> R;
a7b([H|T], R) when is_list(H) -> a7b(T, a7b(H, R));
a7b([H|T], R) -> a7b(T, [H|R]).

a7b(L) -> a5(a7b(L, [])).

% Eliminate consecutive duplicates of list elements.
a8([], _, R) -> R;
a8([H|T], P, R) when P == H -> a8(T, P, R);
a8([H|T], P, R) when P /= H -> a8(T, H, [H | R]).

a8([H|T]) -> a5(a8(T, H, [H|[]])).

a8b([], _) -> [];
a8b([H|T], P) when P == H -> a8b(T, P);
a8b([H|T], P) when P /= H -> [H|a8b(T, H)].

a8b([H|T]) -> [H|a8b(T,H)].

% Pack consecutive duplicates of list elements into sublists.

pack([], _, R) -> [R];
pack([H|T], P, R) when H == P -> pack(T, P, [H|R]);
pack([H|T], _, R) -> [R| a9([H|T], H)].

a9([], _) -> [];
a9([H|T], P) when H == P -> pack([H|T], P, []);
a9([H|T], _) -> a9(T, H).

a9([H|T]) -> a9([H|T], H).

% Run-length encoding of a list.

a4c(L,[H|_]) -> [a4(L), H].

a10h([]) -> [];
a10h([H|T]) -> [a4c(H,H)| a10h(T)].

a10(L) -> a10h(a9(L)).

% Run-length encoding of a list.

a4d(L,[H|_]) ->
X = a4(L),
case X of
1 -> H;
_Other -> [X,H]
end.

a11h([]) -> [];
a11h([H|T]) -> [a4d(H,H)| a11h(T)].

a11(L) -> a11h(a9(L)).

% Decode a run-length encoded list.

unpack([0,_], R) -> R;
unpack([N,C|_],R) -> unpack([N-1,C], [C|R]).

a12([], R) -> R;
a12([H|T], R) when is_list(H) -> a12(T, unpack(H,R));
a12([H|T], R) -> a12(T, [H|R]).

a12(L) -> a5(a12(L, [])).

% Run-length encoding of a list (direct solution).
a13([],P,C, R) ->
case C of
1 -> [P|R];
_Other -> [[C,P]|R]
end;
a13([H|T], P, C, R) when H =:= P -> a13(T, P, C+1, R);
a13([H|T], P, C, R) when H =/= P ->
case C of
1 -> a13(T,H,1,[P|R]);
_Other -> a13(T,H,1,[[C,P]|R])
end.

a13([H|T]) -> a5(a13([H|T], H, 0, [])).

% Duplicate the elements of a list.
a14([]) -> [];
a14([H|T]) -> [H,H|a14(T)].

% https://prof.ti.bfh.ch/hew1/informatik3/prolog/p-99/
repeat(_,0) -> [];
repeat(C,T) -> [C|repeat(C, T-1)].

a15([],_) -> [];
a15([H|T],C) -> a7b([repeat(H,C)|a15(T, C)]).

% Drop every N'th element from a list.
a16([], _, _) -> [];
a16([_|T],C,N) when N rem C =:= 0 -> a16(T, C, N+1);
a16([H|T],C,N) -> [H|a16(T,C,N+1)].

a16(L,C) -> a16(L,C,1).

% Split a list into two parts; the length of the first part is given.
a17([],_,_,L) -> {a5(L),[]};
a17([H|T],N,R,L) when N =:= R -> {a5([H|L]), a5(T)};
a17([H|T],N,R,L) -> a17(T,N,R+1,[H|L]).

a17(L, 0) -> {L, []};
a17(L,N) -> a17(L,N,1,[]).

% Extract a slice from a list.
a18([],_,_,_) -> [];
a18([H|T],I,K,N) when N >= I, N =< K -> [H|a18(T,I,K,N+1)];
a18([_|T],I,K,N) -> a18(T,I,K,N+1).

a18(L,I,K) ->a18(L,I,K,1).

% Rotate a list N places to the left.
a19(L, N) -> SP = N rem a4(L),
if
SP < 0 -> S = a4(L) + SP;
true -> S = SP
end,
{H, T} = a17(L, S),
a7([T,H]).

% Remove the K'th element from a list.
a20([],_,_, L) -> L;
a20([H|T],N,I,L) when N =:= I -> {H, a5(a20(T,N,I+1,L))};
a20([H|T],N,I, L) -> a20(T,N, I+1, [H|L]).

a20(L,N) -> a20(L,N,1,[]).

% Insert an element at a given position into a list.

a21([],E,P,N) when P =:= N -> [E];
a21([],_,_,_) -> [];
a21([H|T], E, P, N) when P =:= N -> [E,H| a21(T,E,P,N + 1)];
a21([H|T], E, P, N) -> [H|a21(T, E, P, N+1)].

a21(L, E, P) -> a21(L, E, P, 1).

%*) Create a list containing all integers within a given range.
a22(A,B) when A > B -> [];
a22(A,B) -> [A|a22(A+1,B)].

SELECT * FROM USER_TABLES

Short

Select COLUMN_NAME from all_tab_columns where table_name=upper('tableName')

http://forums.oracle.com/forums/thread.jspa?threadID=375977

Yesterday I had the joy of having the Oracle 11g install majorly mislead me. Even though it couldn't really work on my windows computer due to it having a dhcp ip, the installer gave me a "warning" that got buried in their amazingly small viewing area, and it let me continue the install. Even better, by letting me log into the db in SQL*Plus, it totally faked me out into believing that the installation was successful. It was only when I tried to work with it in .net that i started getting the annoying tns not running error.

So I search for to see what the problem is, and there are tons of posts in the oracle forums on this error, everyone with a different problem and solution. I dutifully try the different solutions, I get it to "work" according to the solutions, i.e, I get the hellish service to actually run, and yet it still won't work in .net.

And this is RIGHT AFTER INSTALLATION, WHEN THE DAMN THING SHOULD WORK.

So I decided to uninstall and install again. While installing again, I noticed that I got "warning" telling me in a weak worded way that stuff may happen in dhcp if I go ahead with the installation. The stupid feedback should read: "It WON'T WORK. Install the freaking Microsoft loopback Adapter First."

Fortunately this actually fixed the problem.

I don't know if Oracle just likes to prank developers, or if this is some kind of hazing to join the Oracle crowd. This error message is so common and is triggered by so many things that the desperate posts of people are received with a massive yawn by the regulars who tell you to search through their archives to find the solution.

And I guess that their ridiculously small viewing windows at the prerequisite check of the installer, which one cannot adjust, is their way of stating to the world that Oracle is a totally back-end development shop? Do they put interns to create the install GUIs?

I am still angry, and the best part of this is that I actually rested and went to sleep before posting this.

You initialize it like this:

var membership = Membership.Providers["orclmembershipProvider"];
var validated = membership.ValidateUser(user, password);

A bit different than MS's provider. The name of the provider that you give is the one that you put in the web.config tags.

Answer:

grant create session to ;

I had to hunt for this one as well. Maybe the word ACCESS is used for something else.

http://thomas.eibner.dk/oracle/old/

Answer:

grant unlimited tablespace to ;

It took me a while to find this. Unfortunately I closed the window too quickly so I cannot give the link to the place where I found this entry.

Hugo