How did they program the first programming languages?
Nowadays, we know C++ can tell the difference between an int, string etc., but how? We know it expects "()" after a function, but how did they make it so that it can recognize a function? Or what a function even was? They must have been geniuses decades ago, when there were really no resources for this kind of thing in the first place. Fascinating.
All computers have a "machine code". The very first programs are written in machine code.
There is also "assembler" which is a little bit higher abstraction over machine code. You can write anything you want with Assembler.
Above that are simple languages, like Basic or C, which you can also use to write any language you wish.
What is useful these days is the ability to "cross-compile", which is to compile code for a new machine using an existing machine. All you need to do after that is copy the file properly. So, ideally, you could write a new language with whatever language you wish, so long as you have the ability to cross-compile (or something equivalent).
When it comes to actually writing a language, that is a very involved subject. The first languages (FORTRAN, Basic, etc) were very simple because they were written very simply.
After that languages were generally written with a "recursive descent" algorithm, which is very powerful. (You can google it.)
Many languages today are written with a LR parser (or some other form of a lookahead parser). You can read more about types of parsers and get links from Wikipedia: http://en.wikipedia.org/wiki/Parsing
Hope this helps.
There is also "assembler" which is a little bit higher abstraction over machine code. You can write anything you want with Assembler.
Above that are simple languages, like Basic or C, which you can also use to write any language you wish.
What is useful these days is the ability to "cross-compile", which is to compile code for a new machine using an existing machine. All you need to do after that is copy the file properly. So, ideally, you could write a new language with whatever language you wish, so long as you have the ability to cross-compile (or something equivalent).
When it comes to actually writing a language, that is a very involved subject. The first languages (FORTRAN, Basic, etc) were very simple because they were written very simply.
After that languages were generally written with a "recursive descent" algorithm, which is very powerful. (You can google it.)
Many languages today are written with a LR parser (or some other form of a lookahead parser). You can read more about types of parsers and get links from Wikipedia: http://en.wikipedia.org/wiki/Parsing
Hope this helps.
Last edited on
LB :D great resource. I used it in my last compiler attempt. I will probably reference it again at some point now that im working on another compiler.
http://www.catb.org/jargon/html/story-of-mel.html
From "The Story of Mel":
From "The Story of Mel":
| Real Programmers wrote in machine code. Not FORTRAN. Not RATFOR. Not, even, assembly language. Machine Code. Raw, unadorned, inscrutable hexadecimal numbers. Directly. |
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