tl;dr: Short introduction to Parsec for beginner.
- The html presentation is here.
Latin pars (ōrātiōnis), meaning part (of speech).
- analysing a string of symbols
- formal grammar.
Parsing in Programming Languages
|Method||Typical Example||Output Data Structure|
Parser & culture
In Haskell Parser are really easy to use.
- In most languages: split then regexp then parse
- In Haskell: split then parse
To data structure:
Parsec lets you construct parsers by combining high-order Combinators to create larger expressions.
Combinator parsers are written and used within the same programming language as the rest of the program.
The parsers are first-class citizens of the languages […]"
In reality there are many choices:
|Parsec 3||powerful, nice error reporting|
Haskell Remarks (1)
spaces are meaningful
f x -- ⇔ f(x) in C-like languages f x y -- ⇔ f(x,y)
Haskell Remarks (2)
Don’t mind strange operators (
Consider them like separators, typically commas.
They are just here to deal with types.
toto <$> x <*> y <*> z -- ⇔ toto x y z -- ⇔ toto(x,y,z) in C-like languages
Minimal Parsec Examples
whitespaces = many (oneOf "\t ") number = many1 digit symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
" \t " – whitespaces on " \t " "" – whitespaces on “32” “32” – number on “32” – number on "