Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Silon – Adders and Logic Gates in Pure CSS

silon.slaks.net

Post reply on HN
Print view View original

31–40 of 40 posts

Re: Silon – Adders and Logic Gates in Pure CSS

#31

Post by robin_reala »

devsquid wrote: post #10
vardump wrote: post #4

You can implement an adder in CSS? Somehow this reminds me of C++ templates. These things seem to gain power and have new features until they become turing-complete. And beyond...

haha, thats a funny thought. I like CSS. I would love for it to have variables so I could consolidate changes and edit them via JS. Sorta like all the CSS-libraries. o.o am i doing it??

CSS does have variables: http://www.w3.org/TR/css-variables/

Of course, this being the web you’re somewhat limited in browser support: http://caniuse.com/#feat=css-variables

Re: Silon – Adders and Logic Gates in Pure CSS

#32

Post by jonsen »

jacquesm wrote: post #15
pdkl95 wrote: post #13

Earlier quoted context omitted.

Using a lookup table is a valid way to implement something. It is used often for precalculating expensive functions. (trig tables are very common). This is just one extreme of the runtime-vs-memory trade-off.

Lookup tables get very large as the number of potentially valid outputs increases and can do only so much (no way to incorporate state with a lookup table).

(Memory elements are lookup tables with feed back. Very instructive to deconstruct for example the gate diagram of the D-flip-flop 7474 into one table with five inputs and three outputs.)

Re: Silon – Adders and Logic Gates in Pure CSS

#33

Post by TheOtherHobbes »

tolmasky wrote: post #25
pdkl95 wrote: post #18

Earlier quoted context omitted.

The difficulting in actually creating some of these larger lookup tables is, of course, very true. That doesn't mean that sometimes , depending on the problem you're solving, lookup tables can still be a useful (or preferred) implementation method. It is the programmer's job to decide what point on the "using storage" "using CPU time" continuum is appropriate for the current problem. Obviously, larger chained adders…

Yes, but this time it is disappointing. If the website was a tool for learning logic gates, it would be perfectly acceptable and quite clever. However, since the website is saying that it has implemented logic gates in CSS, a natural, if not necessary expectation is that these gates should be composeable, which they are not. Logic gates that can't be fed into each other really strain the definition of a logic gate (i…

Not wanting to be negative here, but I don't get the point of these CSS projects.

CSS isn't Turing complete. It's a (poorly designed) markup tool, not a general symbol processing language. So there's a whole world of stuff it just can't do in any useful way.

Any attempt to make it do this stuff is either going to have to fake it with limited sleight-of-mind, or is simply not going to work.

So "I made s Haskell compiler out of pure CSS" is always going to be disappointing. (If you could make real logic gates, you certainly could make a Haskell compiler. Although it's possible it wouldn't be fast enough for production code.)

Re: Silon – Adders and Logic Gates in Pure CSS

#34

Post by qubex »

TD-Linux wrote: post #20
pdkl95 wrote: post #13

Earlier quoted context omitted.

Using a lookup table is a valid way to implement something. It is used often for precalculating expensive functions. (trig tables are very common). This is just one extreme of the runtime-vs-memory trade-off.

On FPGAs, it's actually how most logic functions are implemented. FPGAs are a big grid of SRAM-based lookup tables, some latches and fixed function blocks, and a whole ton of interconnections.

This is how the famous Connection Machine 2's “one-bit processors” were implemented and programmed too, and basically the connection fabric is roughly analogous.

Indeed one can dynamically any kind of rapidly-reconfiguring FPGA-array into a very peculiar and high-performance general parallel processor.

Re: Silon – Adders and Logic Gates in Pure CSS

#35

Post by talmand »

teraflop wrote: post #12
jacquesm wrote: post #5

In case you're wondering what makes it tick: https://github.com/SLaks/Silon/blob/gh-pages/styles/basic-ga...

Aww, after seeing that I'm a little disappointed. Each CSS file is basically just a giant truth table that describes which state each bit should be in under all possible combinations of inputs. It makes for a cool demo of how simple Boolean circuits work , but you can't really say it's "doing computation" in CSS when all of the actual computation has been done ahead of time. Still, it's clever.

I have to wonder what exactly you expected?

As someone who works with CSS everyday, it's exactly what I expected once I saw it working. How else could it possibly work?

Re: Silon – Adders and Logic Gates in Pure CSS

#37

Post by slaks »

teraflop wrote: post #12
jacquesm wrote: post #5

In case you're wondering what makes it tick: https://github.com/SLaks/Silon/blob/gh-pages/styles/basic-ga...

Aww, after seeing that I'm a little disappointed. Each CSS file is basically just a giant truth table that describes which state each bit should be in under all possible combinations of inputs. It makes for a cool demo of how simple Boolean circuits work , but you can't really say it's "doing computation" in CSS when all of the actual computation has been done ahead of time. Still, it's clever.

Note that that's all computed by LESS code.

https://github.com/SLaks/Silon#implementation-details https://github.com/SLaks/Silon/blob/gh-pages/styles/_operato...

The actual declarations end up being nicely simple; see https://github.com/SLaks/Silon/blob/gh-pages/styles/_themed-...

The CSS is just a truth table, but the LESS (which is Turing-complete) actually contains all of the logic.

Re: Silon – Adders and Logic Gates in Pure CSS

#38

Post by slaks »

TheOtherHobbes wrote: post #33
tolmasky wrote: post #25

Earlier quoted context omitted.

Yes, but this time it is disappointing. If the website was a tool for learning logic gates, it would be perfectly acceptable and quite clever. However, since the website is saying that it has implemented logic gates in CSS, a natural, if not necessary expectation is that these gates should be composeable, which they are not. Logic gates that can't be fed into each other really strain the definition of a logic gate (i…

Not wanting to be negative here, but I don't get the point of these CSS projects. CSS isn't Turing complete. It's a (poorly designed) markup tool, not a general symbol processing language. So there's a whole world of stuff it just can't do in any useful way. Any attempt to make it do this stuff is either going to have to fake it with limited sleight-of-mind, or is simply not going to work. So "I made s Haskell compil…

I built this for fun, and to remind people that CSS can do more than you think. (it should also be a nice tool to help teach adders)

While I would obviously never do something this insane in a real product, I have used CSS for surprisingly much actual logic in real code (empty states for lists, hiding controls that the user cannot use, etc).

See also http://stackoverflow.com/a/5239256/34397

Re: Silon – Adders and Logic Gates in Pure CSS

#40

Post by teraflop »

talmand wrote: post #35
teraflop wrote: post #12

Earlier quoted context omitted.

Aww, after seeing that I'm a little disappointed. Each CSS file is basically just a giant truth table that describes which state each bit should be in under all possible combinations of inputs. It makes for a cool demo of how simple Boolean circuits work , but you can't really say it's "doing computation" in CSS when all of the actual computation has been done ahead of time. Still, it's clever.

I have to wonder what exactly you expected? As someone who works with CSS everyday, it's exactly what I expected once I saw it working. How else could it possibly work?

I don't know, that's the point! Implementations frequently have unexpected behavior that can be abused for computational purposes. For example, you can perform computations on an x86 without actually executing any instructions, by setting up the page tables such that the MMU functions as a rudimentary one-instruction computer. https://github.com/jbangert/trapcc

Real, asymptotically-efficient computations in CSS would require some kind of layer of indirection -- a way to make the styling of one element depend on another one. I'm far from a CSS expert and I don't know if such a thing is at all possible, but it's not out of the realm of possibility.

Off the top of my head, you might be able to get somewhere by requiring the user to put their mouse pointer in a certain location, and using box sizes to trigger the :hover pseudo-class. If the pointer covers multiple overlapping elements, is :hover applied to all of them, or just the topmost?

Post reply on HN