# Compiler

A compiler takes in programs of a language, produces programs of a language.

If we think deeper, what are required of such a function?

A mapping! Different parts of the program should map to the output.

To get this different parts we use which gives us our syntactic tokens, e.g. if, else, let.

Then we use to create an which has an interface we can work with.

We then have to understand the of our source program, and finally use to output program in target language.

## Common tools used

• yacc, bison, (f)lex Not modern but stable. No inbuilt support for unicode.

• ANTLR Modern

• Definite clause grammars https://www.metalevel.at/prolog/dcg https://github.com/indocomsoft/aoc2020/blob/main/16/ans.pl http://csci431.artifice.cc/notes/prolog-parsing.html

• Parser combinators Combining various parsers.