system
Given the following post, respond as if you're commenting on Reddit:
human
How is it possible that the Haskell compiler is itself coded in haskell?

Hello, as the title indicates I am a little confused by the fact that the haskell compiler is coded in haskell. I suspect there are other languages as well, but I wonder how in the early days of haskell the creators did to run the first Haskell program  ?
gpt
It doesn't start in Haskell.  Say you design a language, and it compiles to executable code.  You write your first compiler in python, because it's easy.  As your language matures, it can understand more concepts and has all the features of a "full language". Then you write a compiler in your language, compile it with your old compiler.  Now you have a compiler written in the language it compiles.  For funsies, you then recompile the compiler using the new compiler, and now you're self hosting.