In programming languages, a type system is a logical system comprising a set of rules that assigns a property called a type to the various constructs of a computer program, such as variables, expressions, functions or modules. These types formalize and enforce the otherwise implicit categories the programmer uses for algebraic data types, data structures, or other components (e.g. "string", "array of float", "function returning boolean"). The main purpose of a type system is to reduce possibilities for bugs in computer programs by defining interfaces between different parts of a computer program, and then checking that the parts have been connected in a consistent way. This checking can happen statically (at compile time), dynamically (at run time), or as a combination of both. Type systems have other purposes as well, such as expressing business rules, enabling certain compiler optimizations, allowing for multiple dispatch, providing a form of documentation, etc.
A type system associates a type with each computed value and, by examining the flow of these values, attempts to ensure or prove that no type errors can occur. The given type system in question determines what constitutes a type error, but in general, the aim is to prevent operations expecting a certain kind of value from being used with values for which that operation does not make sense (logic errors). Type systems are often specified as part of programming languages and built into interpreters and compilers, although the type system of a language can be extended by optional tools that perform added checks using the language's original type syntax and grammar.
I have relatives who are mormon... which drives me insane. I am atheist... but am generally accepting of other people's beliefs, although always ready to argue with someone if they want to. However my cousin is sent away to some sort of religous facilitiy for one year where she is complelty cut...
Does anyone know a good online resource for type theory? I've heard that in it, there is a "universal object" which "contains" all other "objects." Is this right? Where can I get the good stuff? I know I can google for it; I'm not a moron. I just want your recommendations instead of a list...
This question relates on the capacitance and the charge stored in each capacitor.
I have my question and diagram in the attachment.Hope that anyone will help me figure out.
Following is an entry from Q is for Quantum by John Gribbin.
infinity There is more (sometimes less) to infinity for a mathematician than to the person in the street. Science-fiction fans and amateur philosophers may be familiar with the idea that, if the Universe is infinite, then not only...
What are the weaknesses and strengths of Russell's type theory? I'm having trouble understanding exactly what makes it weaker than ZF. I've been told its too restrictive, but what exactly makes it more restrictive than ZF?
Are there any objections to ZF?
What type of government do the insurgents in Iraq seek to impose?
If insurgents succeed in establishing a state based on terrorism, would it not be fractious and set Iraqi society back a millennium (a la Afghanistan under the Taliban), or would it ally with one of the existing Iraqi political...
Help! I'm just starting this class and I have no idea what's going on. What I don't understand is, what answer are you supposed to give? My question says "Find the general solution and also the singular solution, if it exists". What the hell does that mean?
Can someone tell me if this...
I've seen people in the homework help forum type mathematical statements such as fractions, exponents, integrals, etc. Anyone know how I can do this? Thanks.
Okay, I have this crazy pulley question where a guy is sitting in a box that is attached to a pulley on the ceiling (the pulley system is ideal). He pulls himself up at a constant velocity -how do i find the force needed for him to pull himself up? (the rope goes around the pulley and back...
Hi everyone,
I was wondering if anybody could suggest a type I receptor that is able to undergo internalization but that is not involved in any type of signal transduction that would lead to apoptosis or proliferation?
Thanking you in advance,
Emily
HARD-DISK woman/Man: She/He remembers everything, FOREVER.
RAM woman: She forgets about you the moment you turn her off.
WINDOWS woman/Man: Everyone knows that she/He can't do a thing right, but no one can live without her.
EXCEL woman/Man: They say she/He can do a lot of things but you...
Assuming that I have an atom that produces two photons having opposite polarization, and I send one toward the event horizon of a black hole and the other is sent to a second observer who does not measure his photon's polarization until enough time has passed to insure that the other photon has...
I was bored and started playing with little pictures using Japanese stuff:
http://bad-sports.com/~archive/images/avatar.gif
http://bad-sports.com/~archive/images/yinyang.gif
Well, what type of music does everyone listen to?
As for me, I'm into Power Metal mainly.
Some of my favorite bands are...
- Blind Guardian
- Edguy
- Ayreon
- Kamelot
- Angra
- Symphony-X
- Children of Bodom
- Sonata Arctica
To all futurists:
I have written an essay at Project Global Consciousness about the two things humanity needs to lose before we have a hope of getting to the next level of civilization.
This will be the first time the page is open for comments, and I would enjoy reading your thoughts...
Hey guys;
This is a Dell Dimension 8100. It is a few years old. I'm looking to get a new case for it (rack mount), but I don't know what type of motherboard it is. I fear it may be proprietary.
Click here:
http://www.think-evolution.com/mycase.jpg
I guess if its proprietary, I may...
We're doing a project for my engineering tech class, and i need to conduct a survey, we'd be really obliged if u could answer the survey questions.
1. When thinking about bridges, what is the first bridge that to your mind?
2. Why?
3. If crossing a bridge, do you look over the edge?
4...
Hey guys;
Is there currently any type of Wireless USB bridge thing?
What I mean.. I have a laptop, and when I use my digital camera I have to plug it in the back of my PC, which means I have to pull out the USB cable and bring it to my laptop, etc. Is there any way I can have the USB...
is there a way to tell the activation energy for a reaction mathmatically just based on what the reaction is, or what it contains? or do you just have to know what it is, based on looking off a table or some other way of finding that data.
lets say I have a hypothetical reaction:
X + Y -> XY...
In Dr. Michio Kaku's excellent book entitled, "Hyperspace", he discusses about three kinds of civilizations:
Type 1, 2, & 3 Civilizations
A Type I civilization would be able to manipulate truly planetary energies. They might, for example, control or modify their weather. They would have...
are either going to be political or about news... Well, this one is about the paparazi. I think that the press gets too personal with people, and they never give them their privacy. These are people too, they deserve their privacy. Must we be reminded of Princess Diana's tragedy to see this...
Hey guys, in my microbiology class last semester my prof mentioned that the plague, caused by Yersinia pestis, which was in Europe, etc. He said that the reason that Y. pestis killed so many people was that it had the same surface antigens as type B blood, therefore people with (type B and type...
Hi guys..
I am a new member of physicsforums.com (I am a science student at the pre-undergrad level). I am unable to solve a problem involving motion of a chain along a circular track, in classical mechanics. The problem is from an old book on mechanics. Please read the problem (below) and...
I'm writing to you, whom I hope to call my friends, rather than write Dr. Kaku personally, which would not only be an unproductive step toward my goal, but I quickly realized that with the existence of this forum, my real goal is here, and is certainly furthered by my membership with you.
I...
The copper-oxygen planes that
are believed to be responsible for superconductivity are separated by
many insulating layers layers. So there might not be much overlap between
atomic orbitals between separated Cu-O planes. However, electrons can
still tunnel through the insulating layers. This...
Would you please tell me what it is in an internet connection ?
I see it written in my firewall windows, I am only curious to know what it really means...
Thanks
Hi Forum,
I am looking for information on Type IV and above civilizations.
If anyone has any references I would appreciate it a lot. I understand an astronomer called john barrows has written on this but I can't find anything on google on this. nor has a 'Type IV civilization' search...
http://arxiv.org/abs/astro-ph/0402512
We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration. These objects, discovered...
Dr. Kaku, Carl Sagan, and the majority of the scientific community recognises the need for society (esp. in the United States) to wake up to the threats that human activity, through pollution and nuclear energy, pose to the future of humanity and the planet. Not to mention future threats from...
This is a question that has been hunting me for ages: which type of wood would be best for constructing a apparatus to hold the largest amount of weight with the smallest mass? I would appreciate it very much if someone can give me some help.
27O2 + 4C4H9NH2 -> 16CO2 + 22H20 + 2N2
What classification would you give this reaction?
-------------------------------------
Its a decomposition reaction . . . why?
My teacher told me that combustion reaction's always have a Carbon/hydrogen compound on the reactant side w/ O2, and...
Hi i had a question wondering ok i have heard and read that most people are blood type O. Well since O is a recessive gene how is it that there are so many O types when the other ones should be dominating. I just don't understand it?
Some of you must have seen his random specials. Card tricks are one thing, but he takes it to extreme levels of insanity.
For those of you who haven't seen both magic specials (one is remarkably underplayed on tv), here are some things he's done.
Had people write their name on a card...
I'm a Canadian student that is going into engineering next year, and I don't know what type of engineering I should go into. In Canada, some schools offer a common first year and you choose your discipline in the second year. The thing is that these schools do not offer aerospace...
It's fun to think about the far-out Type II and III civilizations, but how close are we now to Type I?
M. Kaku says the output of our star is about "a billion trillion trillion ergs per second". That is, if I have done the arithmetic correctly, 10^33 ergs/sec or, dividing by 10^7, 10^26...
This is something that mystifies me --
If the first stars were composed of only hydrogen and helium, why does a Type 1a Supernova show virtually no hydrogen in its spectrum? It seems logical that we would see an abundance of hydrogen.
Thanks!
Type 1, 2, & 3 Civilizations
Note to newcomers: This is a very old thread that does not meet the current forum guidelines and has therefore been closed.
In the excellent book entitled, "Hyperspace", theoretical physicist Michio Kaku mentioned about three kinds of civilizations:
Type 1, 2, & 3...
In my calculus course I was tough to solve differential equations by separation and then integrating
For instance
dv/dt = a
dv = a*dt
v= a*t + c (c is a constant of integration)
then if I was given an initial condition such as v(0)=Vo I would substitute into my general solution
and...
I'm coming towards the close of a good (yet dated) book: Men of Mathematics, by E.T. Bell. For those of you who haven't read it, the book gives a detailed accounts of the lives up the many recent greatest mathematicians and also touches upon the work they did.
Is there a book that would be...
Hi,
Please forgive me, I know not whether this is the appropiate forum to post to or whether I should ask, but...
I am inquiring what type of Physics software that is needed, I'm mostly interested in High School level. What would be benificial to the student? What could help the student...