Macro pipeline 

macro_rules! pipeline {
    ($doc:expr => $($transform:expr),* $(,)?) => { ... };
}

Macro for creating transformation pipelines with a more functional syntax

Example

use markdown_ppp::ast::*;
use markdown_ppp::ast_transform::*;
use markdown_ppp::pipeline;

let original_doc = Document {
    blocks: vec![Block::Paragraph(vec![Inline::Text("  hello  ".to_string())])],
};

let result = pipeline! {
    original_doc =>
    |d: Document| d.transform_text(|s| s.trim().to_string()),
    |d: Document| d.normalize_whitespace(),
};