Writing your own programming language and compiler with Python
Hey, if you do read the book and end up creating your very own programming language, feel free to share it with the rest of us here. Till then, happy programming! Register for our free webinar on April 27, at pm BST and learn how to extend the scope of #ITIL4 to non-IT areas of your organization. Jan 05, · A programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Why? Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication, because is hard for humans to type Reviews:
And yet, I still made a completely new language. And it works. So I must be doing something right. Technically any language could be compiled or interpreted, but one or the other usually makes more sense for a specific language. Generally, interpreting tends to be more flexible, while compiling tends to have higher performance. But this is only scratching the surface of a very complex topic. What should i be doing with my life highly value performance, and I saw a lack of programming languages that are both high performance and simplicity-oriented, so I went with compiled for Pinecone.
This was an important decision to make early on, because a lot of language design decisions are affected by it for example, static typing is a big benefit to compiled languages, but not so much for interpreted ones. Mzke the fact that Pinecone was designed with compiling in mind, prograamming does have a fully functional interpreter which was the only way to run it for a while.
The first stage is a string containing the entire input source file. The final stage is something that can be run. This will all become clear as we go through the Pinecone pipeline step by step.
The first step in most programming languages is lexing, or tokenizing. A token is a small unit of a language. A token lanugage be a variable or function name AKA an identifieran operator or a number. The lexer is supposed to take in a string containing an entire files worth of source code and spit out a list containing cmputer token. Future stages of the pipeline will not refer back to the original source code, so the lexer must produce all the information needed by them.
Compuetr reason for this relatively strict pipeline format is that the lexer may do tasks such as removing comments or detecting if something is a number or identifier. The day I started programmming language, the first thing I wrote was a simple lexer. Soon after, I started learning about tools maake would supposedly make lexing simpler, and less buggy. The predominant such tool is Flex, a program that generates lexers.
From that it generates a C program which lexes a string and produces the desired output. I opted to keep the lexer I wrote for the time being. My lexer is only a few hundred lines long, and rarely gives me any trouble.
Rolling my own lexer also gives me more yout, such as the ability to add an operator to the language without editing multiple files. The second stage of the pipeline is the parser. The parser turns a list of tokens owh a tree of nodes.
At least in Pinecone, the AST does not have any info about types or which identifiers are which. It is simply structured tokens. The ma,e adds structure to to the ordered list of tokens the lexer produces. To panguage ambiguities, the parser must take into account parenthesis and the order of operations.
Again, there laanguage a decision to make involving a third party library. The predominant parsing library is Bison. Bison works a lot like Flex. You write a file in a custom format that stores the grammar information, then Bison uses that to generate a C program that will do your parsing.
I did not choose to yuor Bison. With the lexer, the decision to use my own languqge was fairly obvious. The major ones are as follows:. There is a subtle but very significant difference between the action tree and the abstract syntax tree.
It took me quite a while to figure out that there even should be a difference between them which contributed to the need for rewrites of the parser. Put simply, the action tree is the AST with context.
Proframming context ypur info such as what type a function returns, or that two places in which a variable is used are in fact using the same variable. Because it needs makw figure out and remember all this context, the code that generates the action tree needs lots of namespace lookup tables and other thingamabobs.
Once we have the action tree, running the code is easy. This is the interpreter in action. But compiling is harder than interpreting. There are a few possible approaches. This sounded like languwge good idea to me at first.
Unfortunately, writing a portable compiler is not as easy as writing some machine code for each language element. Because of the number of architectures and operating systems, it is impractical for any individual to write a cross platform compiler backend. LLVM is a collection of compiler tools. It seemed like the perfect choice, so I jumped right in.
LLVM, while not assembly language hard, is gigantic complex library hard. I wanted some sort of compiled Pinecone and I wanted it orogramming, so I turned to one method I knew I could make work: transpiling.
This currently works for almost all Pinecone programs though there are a few edge cases that break it. It is not a particularly portable or scalable solution, but it works for the time being. I suspect no mater how much I work on it, the transpiler will never be completely stable and the benefits of LLVM are numerous. What does inflammation of the cervix mean you do want to make one yourself, I highly recommend it.
There are a ton of implementation details to figure out but the outline here should be enough to get you going. I have very few regrets when it comes to Pinecone development. I made a number of bad choices along mke way, but I have rewritten most of the code affected by such prograkming.
Right now, Pinecone is in a good enough state that it functions well and can be easily improved. If this article was helpful, tweet it. Learn to code for free. Get started. Forum Donate. High Level Design A programming language is generally structured as a pipeline. Lexing The first step in most programming languages is lexing, or tokenizing. Tokens A token is a small unit of a language. Task of the Lexer The lexer is supposed to take in a string containing an entire howw worth of source code and spit out a list containing every token.
Flex The day I started the language, the first thing I wrote was a simple lexer. My Decision I opted to keep the lexer I wrote for the time being. Parsing The second programmkng of the pipeline is the parser. Parser Duties The parser adds structure to to the ordered list of tokens the lexer produces. Bison How to make your own computer programming language, there was a decision to make involving a third party library.
Why Custom Is Better With the lexer, the decision to use my own code was fairly obvious. This can be automated but it becomes a pain when switching between build systems. A custom parser may not be trivial, but it is completely doable. Writing a lexer and parser is a tiny percentage of the job of writing a compiler. Using a generator will take up about as much time as writing one by hand, and it will hlw you to the generator which matters when porting the compiler to a new platform.
And generators also have the unfortunate reputation clmputer emitting lousy error messages. Running the Action Tree Once we have the action tree, running the code is easy. Build My Own Compiler This sounded like a good idea to me at first. Transpiling I wanted some sort of compiled Pinecone and I wanted it fast, so I turned to one method I knew I could make work: transpiling. Interpreted languages are generally easier design, build and learn.
When it comes to lexers and lanyuage, do whatever you want. There are valid arguments for and against writing your own. Oyur from the pipeline I ended up with. A lot of how long to get herpes test results back and error went into designing the pipeline I have now. These interpreters can be as short as a few hundred lines.
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May 15, · There are approximately programming languages being used today by the world-wide code community. Some of them are made specifically to run on your web-browser and others are made to run on. Make Your Own Programming Language Part 0 This is the intro to a 5-part tutorial on how to implement a programming language. It is intended for people with some programming experience, who want to know how their compiler, interpreter or virtual machine works. If you want to be creative in creating a programming language in C++, you don't start from a parser. There is nothing creative in writing a primitive parser. It's like making paper if you want to write a letter. If you want to write a letter, you concentrate on the content. If you want to "Make a Programming Language" you start from the grammar.
This is the intro to a 5-part tutorial on how to implement a programming language. It is intended for people with some programming experience, who want to know how their compiler, interpreter or virtual machine works. Hint: it's not magic. This installment explains why you might want to make your own programming language, and why this tutorial is better than others.
Feel free to skip directly to Part 1 if you're impatient. Note: here and there I'm going to reference advanced programming topics. You can follow the links usually to Wikipedia at your leisure. Don't worry, it's all rather easy, actually. There are hundreds of programming languages out there, some of which have hundreds of dialects BASIC Remember the exhilarating feeling you had when you first made a computer follow your instructions?
The fun is double when you make the machine understand the instructions in the first place. Many, if not most programming languages were made for fun. While you may be perfectly happy with PHP or Java most of the time, there are tasks much better expressed in other, more specialized languages. Can you imagine accessing databases whitout SQL , or processing strings whitout regular expressions?
Well, many other programming tasks can benefit from domain specific languages , as they are called. If only you knew how to design and implement your own Reason three: For better understanding Nobody understands a programming language better than the man who created it. It's an eye-opening experience. But even if you never use a language of your own, making one will help you understand how the languages you do use work on the inside. You will be a better programmer ever after.
After completing the whole tutorial, I learned there was a Scratch programming language already, kind of an educational Smalltalk for small children.