Going REPLing with Haskeline
So you went ahead and created a new programming language, with an AST, a parser, and an interpreter. And now you hate how you have to write the programs in your new language in files to run them? You need a REPL! In this post, we’ll create a shiny REPL with lots of nice features using the Haskeline library to go along with your new PL that you implemented in Haskell.
So you went ahead and created a new programming language, with an AST, a parser, and an interpreter. And now you hate how you have to write the programs in your new language in files to run them? You need a REPL! In this post, we’ll create a shiny REPL with lots of nice features using the Haskeline library to go along with your new PL that you implemented in Haskell.
For the purpose of this post, let’s assume that we have created a new small Lisp2, just large enough to be able to conveniently write and run the Fibonacci function that returns the nth Fibonacci number. That’s it, nothing more. This lets us focus on the features of the REPL3, not the language.
We have a parser to parse the code from text to an AST, and an interpreter that evaluates an AST and returns a value. We are not going into the details of the parser and the interpreter, just listing the type signatures of the functions they provide is enough for this post.
