Views expressed here are my own and do not represent the opinions of any entity that I was, am or will be involved with. Then you feed this into several tools like Bison and Yacc which generate a bunch of C code that you the need to modify or link into whatever programming language you are actually writing in. The other option is to manually write a parser in your preferred language, which is slow and error prone.
Imagine if your description of the thing you wanted to parse, the grammar, was also the parser? What if you could just run the grammar directly, then add hooks only where you want? Ohm is a new kind of parsing system. With Ohm you write your format definition in a very flexible syntax in a.
Hex and octal. Scientific notation. A leading negative digit. Parsing numbers is easy. Doing it right is hard. To build this code by hand would be difficult and buggy, with lots of special cases which sometimes conflict with each other. A regular expression could probably do it, but would be ugly and hard to maintain. Every parser in Ohm involves three parts: the grammar , the semantics , and the tests.
I usually pick part of the problem and write tests for it, then build enough of the grammar and semantics to make the tests pass. Then I pick another part of the problem, add more tests, update the grammar and semantics, while making sure all of the tests continue to pass.
Even with our new powerful tool, writing parsers is still conceptually complicated. Tests are the only way to build parsers in a reasonable manner. An integer is composed of a sequences of digits next to each other.
The semantics are essentially a bunch of functions matching up to each rule in the grammar. Each function will be called when the corresponding rule in the grammar is parsed. The Number function above will be called when the Number rule in the grammar is parsed. The grammar defines what chunks are in the language. Our semantics functions can do anything we want, such as print debugging information, create objects, or recursively call toJS on any sub-nodes.
By testing it. Lots and lots of testing. Every possible edge case needs a test. With the standard assert API, here is a test function which matches some input then applies our semantics to it to turn it into a number, then compares the number with the expected input.
Now we can write a bunch of tests for different numbers. If the match fails then our script will throw an exception. If not it will print success. Add this to the script. The first two succeed and the third one fails, as it should. Even better, Ohm automatically gave us a nice error message pointing to the match failure. Change the grammar. This changes the Number rule to point to either a float or an int. The means or. This means there must be at least one digit before the period and at least one after.
Since we now have new rules we need new action functions: one for int and one for float. First, int and float and Number all have matching grammar rules and functions. However, the action for Number no longer does anything interesting. In other words the Number rule simply returns whatever its child rule matched. Since this is the default behavior of any rule in Ohm we can actually just leave the Number action out.
Ohm will do it for us.
You can't get around this. Even if all of your variable and function names are in French, you'll still need to have English keywords lying around. Your clients will have to live with this. Your code fragment works as-is. Well, except for the curious way your browser is masculine.
I highly suggest you do not do this. I also think this is not possible. Not only are you throwing away tons of documentation which uses only english but you are making it very difficult for non-french speaking people to code with your application.
The Ugly American Programmer. As Jeff pointed out in a recent blog post , Eric Raymond notes that functional English is required for true hackers :. Back around I learned that many hackers who have English as a second language use it in technical discussions even when they share a birth tongue; it was reported to me at the time that English has a richer technical vocabulary than any other language and is therefore simply a better tool for the job. For similar reasons, translations of technical books written in English are often unsatisfactory when they get done at all.
On a related note, also pointed out in Jeff's post, Wikipedia keeps a list of non-English based programming languages. Programming language keywords are fixed. The browser can't translate them from one spoken language to another. Functions you create yourself can be in any spoken language you chose. You are perfectly able to write your own variables, functions and APIs in other languages; however, the vast majority of existing APIs are going to be in English and there is no way for the browser to understand that you ment navigator when you write navigateur.
Ostensibly, you could write a translation framework that would translate French keywords and French API calls into their English counterparts, but that would be a whole lot of work. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.
Add a comment. Active Oldest Votes. Mark Dickinson Mark Dickinson 6, 3 3 gold badges 26 26 silver badges 41 41 bronze badges. Great idea about the variable and function names. I suppose you could end up with a mini api for the target language, but it would be so specialised, I can't see how it would help in the long run.
This is because the name variable's declaration is hoisted raised to the top of the function and the assignment for the variable stays at the same line while the age declaration and assignment stays at the same line. Hoist problems can happen unexpectedly, and that's why you should use let instead of var. Just like HTML, sometimes we may want to put a note beside our code which does not need to be executed.
But that's not all. Say we wanted to find the average of three numbers. The code for this would be:. Doing this outside of a function may not hurt, but if we had to do that in many places? Then, we'd have a function like so:. As you'll notice in findAverage 's declaration, we have n1, n2, n3 in the parentheses. These are parameters, which serve as placeholders for values that would be provided when the function is to be called. The code block uses those placeholders to find the average, and the return keyword returns the average from the function.