What is the exact difference between LLVM Flang and LFortran?

[Beliavsky]

@Ashok

Sorry for this question, because I don’t know any thing about compilers, I am just trying to understand.
If LFortran compiler is written in C++, I what way it will be faster than C++? I understand that compiler is a program that converts source code into binary. If that is written in C++, then it is another C++ program. Then Fortran becomes a higher level C++. How then it becomes another language ? Are there any specific rules of memory allocation in Fortran compiler ? Or what makes it a Fortran language ? Semantics ?
If I write
print*, “hello world”
If this is processed by a C++ program, then I have written a higher level C++ that’s all ! Or am I missing anything here ?

I don’t think there is a connection between the language a compiler is written in and how fast the resulting programs are. If a Fortran program does not follow the syntax rules of C++ it is not a C++ program, regardless of the compiler implementation language.

I have thought about whether Fortran is a subset of C (or the reverse), but the idea has to do with Fortran/C interoperability. If any standard-conforming C function can be called from a Fortran program, without a speed penalty, and if all platforms with Fortran compilers also have C compilers, maybe one could say that Fortran contains a C subset with distinct rules.

[implicitall]

Five parts of a compiler are Lexical Analysis, Parsing, Semantic Analysis, Optimization, and Code Generation. These slides show a little example of each related to English. http://web.stanford.edu/class/cs143/lectures/lecture01.pdf