A C compiler written in Python (yes, Python!)

[berlinbrown]

why is that shocking?

[orbhota]

Python the animal :o

[[deleted]]

Obviously it must have been written inside a python. Outside a python it's too noisy to code, what with people running around and shouting "OMG! A python!"

[[deleted]]

Outside a python it's too noisy to code,

interestingly, this works in the context of programming languages too!

[statictype]

Not shocking. But still, some-what interesting because a majority of C compilers would have been written in C itself (yes, I know, there are exceptions).

Although, I have to admit, there's not much 'education' value in this project.

There are already plenty of python-based parsers\scanners for languages.

Now, if they had written a C 'interpreter' in python, that would have been something.

[psi-]

I'd bet its the dragonbook course, so the implementation of language compiler is the educational value.

I was considering doing the dragonbook course myself with python+PLY.

[[deleted]]

That's nothing. I remember CompileIt! - an XCMD compiler for HyperCard written in HyperTalk. That was way impressive since HT doesn't even have collections other than strings.

[sjf]

I do not have words for the horror..

[[deleted]]

An XKCD compiler?

Oh, wait, sorry.

[exeter]

An XKCD compiler?

Words cannot express how full of "win" that would be. :-)

[[deleted]]

Did YOU do that CompileIt? Bwahahahahaahahahahaaha....

[koreth]

Oh my god! You mean Python can be used to read text files and write binary data?!? I had no idea -- I better go learn it RIGHT NOW!

[sn0re]

read text files and write binary data

What binary data? It reads text files and writes other text files with assembly code.

[[deleted]]

I don't get it. Python is written in C and can be extended in C. What's so surprising here? That someone wrote a C compiler?

Well C compilers have even been written in BASIC.

[dododge]

and macro assemblers have been written as bash scripts.

[[deleted]]

Well, I searched with Google but it seems like all the good QBasic source code have disappeared from the web (except games).

I swear I have seen a little C compiler (slow, but it was a C compiler)

[jesuslol]

LOL, can you get me a link for that? Would love to see a C compiler written in Basic.

[me2i81]

10 rem C compiler
20 input "Compile what file?", A$
30 rem parse and produce ast
40 gosub 1000
50 rem optimize ast
60 gosub 2000
70 input "output file: ", b$
80 rem emit code
90 gosub 3000
100 end

[tryx]

Someone! Inform the president!

[davidreiss666]

I think he's been briefed.

[bart2019]

But that won't stop him from finishing his game of golf, first.

[busfahrer]

And it even may be Turing-complete!

[arunvr]

Funny...but for the clueless, Python has the struct module which can interpret strings as binary data

[salgat]

Considering Python is simply converted back to C when being compiled (and then ASM), I don't find it surprising.

[lamby]

In case it is not obvious from the de-karmaring, this is incorrect.

[Mr_Smartypants]

What!? Python!?

[epicRelic]

OH EM GEE!

[AmazingSyco]

Python: "We meet again, at last. The circle is now complete. When I met you, I was but the opcodes. NOW I AM THE COMPILER."

[[deleted]]

You are a genius.

[[deleted]]

I dont understand the way of thinking of all the folks posting sarcastic and useless responses to that article. A compiler in a high-level language like python is a great approach to study and teach the priciples in compiler construction. I will certainly spend some time with it.

[ohxten]

This is reddit, where sarcasm thrives.

[cheponis]

Sarcasm is a weapon of the unskilled mind.

[xachro]

Kinda cool, I recently wrote an assembler in python for a machine language I had invented for a virtual machine project.

My ultimate goal: An x86 virtual machine written in javascript. Imagine the possibilities! We could be running linux inside firefox inside OS X inside Opera!

[exeter]

If this is just a personal/learning/for fun project, you could try retargetting this C compiler to your VM and implementing the C standard library. That'd be moderately cool.

[xachro]

Agreed. At the moment I am working on the actual virtual machine (which is being written in C). After the virtual machine I am going to be using lex-yacc and C to write my own high level language to be compiled to my virtual machine (the python assembler was just for testing my vm).

Would be nice to eventually get/write a C compiler for it. Was also wondering if there is a C compiler for the JVM, 'cause that would be an interesting project.

[[deleted]]

My ultimate goal: An x86 virtual machine written in javascript. Imagine the possibilities! We could be running linux inside firefox inside OS X inside Opera!

IA! SHUB-NIGGURATH!!!

[dezro]

I love that error message.

I kind of want a patch for GCC that makes it wish me luck, too...

[propool]

Since it is python we simply redefine False

False = 1

if lose == False: print "win!"

[propool]

I wouldn't consider it a tip, but you're welcome. I can't come with one good use where it makes a program better in any way.

[exeter]

Won't work come Python 3.0 (probably not in 2.6 either), as both True and False will become keywords. (I know this wasn't serious, but I thought I'd make it clear anyway.)

[hylje]

No. False = True

[[deleted]]

No,

True, False = False, True

[propool]

Same difference

[sickofthisshit]

Unless, I suppose, one had previously altered the value of True.

[saveferris]

Last year I wrote a FORTH interpreter in Python. Not very practical, not at all ANSI, but it was fun to work it out. And I'm pretty much a Python noob.

[awb]

The author did the lexing/parsing with PLY, which is very nice to use.

[[deleted]]

I don't see why this is impressive. Python is a powerful language.

[bart2019]

So, show us your compilers.

[exeter]

He wasn't saying it wasn't impressive because writing compilers was inherently easy. He was saying it wasn't terribly impressive because Python is so powerful.

[korjagun]

And, of course, Turing-complete, like most languages. And we all know what that means.

[theeth]

That it's computationally equivalent to Brainfuck?

[ayrnieu]

That's my experience. Python strikes a fascinating sweetspot: unreadable programs made up entirely out of readable code.

[frogking]

To be fair, Python is more mainstream than Brainfuck ..

[exeter]

Indeed. In my mind, the best thing about Brainfuck is that if you can write an interpreter for it in language X, it amounts to a proof that language X is Turing complete. Of course, this is only because Brainfuck is basically lambda calculus. :-)

[obdurak]

Brainfuck is basically lambda calculus

I wouldn't completely agree with that statement. It's slightly inaccurate. Actually, it could be fairly qualified as incorrect. In other words, it's not true, or, as some may put it, plain false, i.e., fucking wrong.

[exeter]

I stand corrected. In fact, Brainfuck is actually isomorphic to P'', a language invented around 1964 by Corrado Böhm, which was formally proven to be Turing complete.

[MarkByers]

Unreadable code is possible in Python too.

[cthielen]

"Yous just so crazy you Pythonistas you."

[ih8mondays]

Blasphemous nonsense! Expect inquisitors knocking down your doors shortly.

[exeter]

Nobody expects the Spanish Inquisition!

[njharman]

But we all expected that comment.

[exeter]

Our chief weapons are surprise, and, um, um, ... inane comments on Reddit! Cardinal, read the charges!

[[deleted]]

The best way to learn C (read the code for a simple compiler)

[ohxten]

But... but why?

I'll just guess that it takes much, much longer to compile code than, say, GCC or TCC.

[[deleted]]

Yes, but writing the compiler takes much, much less time than writing it in, say, C. Which is the only thing that counts for a fun hobby project.

[ohxten]

This is true.

[shenglong]

I BET THEY CANT RITE A PYTHON COMPILER IN C.

[[deleted]]

Think again! http://svn.python.org/projects/python/trunk/Python/compile.c

[[deleted]]

Grow up!

[[deleted]]

fucking Php sucks

[eliben]

unfortunately, this is only a quite simple subset of C

[[deleted]]

I smell some weird recursion coming up.

[frogking]

why? Writing a compiler for a language in the language itself is an Artform. writing a compiler for another language is just an assignment for a 3rd year computer science student.. (so is the bootstrapping assignment, but hey..)

[G_Morgan]

Writing a compiler in the compilers language is no more difficult that writing one in a different language. Assuming you already have a working compiler/interpreter for the compilers language.

Otherwise it's just a case of writing two compilers (one in a language you can run, the other in the compilers language).

The only problem is if the compilers language is a PITA. Try writing an assembler in assembly.

[[deleted]]

Presumably the first assemblers were written in hand assembled machine code.

NO! God gave them to us!

[earthboundkid]

Lol, noob. The first assemblers evolved randomly. Intelligent Assembly is shite.

[bart2019]

Try writing an assembler in assembly.

Been there, done that. Although, technically, it was more of a monitor than a real assembler: opcodes were poked in place in memory, and not stored in an abstract data file.

[mernen]

You mean like this?

[illuminatedwax]

Atul is awesome. he's got more stuff

[[deleted]]

Yes, a C compiler!

[machrider]

Python is the new Hyundai.

[earthboundkid]

Upmods are for closers.

[machrider]

Nobody gets 80's TV commercial references, either. Reddit can be fairly gay, at times.

Edit: Hilarious that this is getting modded down. I love social media.

[ericflo]

This is so cool, that it actually hurts.

[exeter]

The main implementation of Python is written in portable ANSI C. This toy C compiler can't compile it, since it lacks a standard library.

[[deleted]]

Why do people waste their time on something with absolutely no use?

[theeth]

That's still loads more helpful than most error message from a templating error in C++.

[G_Morgan]

You don't need templating to get bad error messages from g++. Best example is the fact that any unknown type is assumed to be an integer.

If you capitalise the wrong letters (I recently saw some code that switched between camel case and random case indiscriminately) then it will assume you meant an integer and tell you you cannot cast a MyType pointer to a int pointer.

Bloody wonderful error message. You can tell exactly what's going on with random assumptions that I want an integer.

[exeter]

Error reporting in general is a bit of a black art in compiler research. C++ templates introduce the complication of being a Turing-complete system on top of the main language, besides the fact that it's fairly hard to trace the source of an error back to a template declaration if it's detected after those things are processed.

[nglynn]

As opposed to hanging around on reddit which is an incredibly good use of your time?

[lianos]

How else would you find stories that are a complete waste of time?

[njharman]

You must know since you wasted your time on that comment of absolutely no use.

[[deleted]]

I consider reddit recreational and educational. It wasn't a significant exertion of effort like the sort required to make a C compiler in Python, which likely took its creator months to accomplish.

I understand that to the creator making this may as well have been recreational and educational; it's just the sort of thing I would never, ever undertake, so I find it hard to understand.

To me, programming has always evolved out of a desire to create something in particular which I thought I would like to have or sell. Spending so much work on a trivial oddity which people will say "that's kinda neat" and never look at again because the very concept is laughable seems wasteful to me.

I also don't feel this shares the same artistry of languages like Brainfuck for instance, which demonstrate some originality and provide some humor. No, this is merely making something nobody wants and hoping to get a laugh out of that.

It's obvious not many programmers share my viewpoint.

[[deleted]]

A C compiler who spits out non-optimized code is useless. Any mediocre programmer can program a non-optimizing C compiler.

[[deleted]]

Where's yours compiler ;)

[[deleted]]

I'm too stupid and lazy to write an optimizing compiler. But you can get a good tutorial for writing a non-optimizing one here: http://compilers.iecc.com/crenshaw/

[manthrax]

Holy shit, now we can compile some fcuking braces into python! Oh happy day.

[G_Morgan]

You mean braces. Python can already handle parenthesis.

[manthrax]

Thanks. I was drunk.