notugly

Simple and generic pretty-printing library, heavily based on A prettier printer.

How to use

To define pretty-printing for a type, implement the Format trait using the various utility functions:

• nil for a null element

• text to create a string into a document

• nest to indent a document

• cat to concatenate two documents

• group and group_with to add the flattened layout as an alternative.

• fold, spread, stack and fill to collapse a list of documents in various ways

To make it easier to define a structure, some operators are defined:

• x & y == cat(x,y)
• x + y == x & text(" ") & y
• x / y == x & line() & y
• x * y == x & group(line) & y

See the examples/ directory for fully-featured examples.

Example : S-Expressions

use notugly::*;

enum SExpr {
    Number(i32),
    Call(String, Vec<SExpr>),
}

impl Format for SExpr {
    fn format(&self) -> Document {
        match self {
            SExpr::Number(n) => text(format!("{n}")),
            SExpr::Call(name, v) => group_with(
                "",
                group(text("(") & text(name) & nest(2, line() & stack(v))) / text(")"),
            ),
        }
    }
}
fn main() {
    let big_eq = sexpr!(add (mul 2 6) (div (mul 4 (mul 3 2 1)) (add 1 (sub 3 (add 1 1)))));

    println!("{}", big_eq.pretty(40));
}