22nd November
Extending the interpreter
For the most part, the interpreter is complete but not very useful as is. There are few key things missing. Namely, support for strings, arrays & hashes. In this section will be adding those in.
Strings
Strings, are not very different from integer literals and can use the string type of the underlying
language (in our case go).
The steps were the same as the ones we followed for adding support for integer literals. But, I realized that I had forgotten what some of the code did :D, no surprise there I suppose, as the lexer was written almost two months ago.
Adding support for strings in the lexer
Currently, if you have a look at the lexer.go. You'll notice that invalid strings are not caught:
if l.ch == '"' || l.ch == 0 {
break
}This will be improved next, so that the parser can return an error instead. Once that's done, I will look
into escape sequences. \, \t, \n
Parsing strings
Currently, parsing the string is really simple. All we did is register a prefix to parse string literals. All this parsing function does is return an ast. This will be improved upon, to return errors for strings that are not closed.