pandoc-unicode-math

If you prefer Markdown to Latex because of its readability, then why not improve the readability of math expressions as well? Just use the power of Unicode!

What does this filter do?

This Pandoc filter replaces Unicode math symbols and greek letters like ∀, ∈, →, λ, or Ω in math environments by equivalent Latex commands like \forall, \in, \rightarrow, \lambda, or \Omega. That means you can write expressions like these in Markdown and still get Latex's superior math typesetting when converting to PDF:

α → β ≡ ¬α ∨ β ≡ ¬(α ∧ ¬β)

∀ x ∈ \{ 2, 4, … \}, ∀ y ∈ ℕ : (x ⋅ y) mod 2 = 0

ℕ ⊂ ℤ ⊂ ℝ

Now compare them to the same expressions written with Latex commands:

\alpha \rightarrow \beta \equiv \neg \alpha \lor \beta \equiv \neg (\alpha \land \neg \beta)

\forall x \in \{ 2, 4, \dots \}, \forall y \in \mathbb{N} : (x \cdot y) mod 2 = 0

\mathbb{N} \subset \mathbb{Z} \subset \mathbb{R}

If you prefer the Unicode variant, this filter is for you!

A complete list of symbols that are replaced by this filter can be found in the src/Symbols.hs file.

Usage

1. Get binaries here and put them in your PATH. Be careful to choose a release that matches your Pandoc version. If necessary, you can build from source (see below).

2. Write a Markdown document containing Unicode characters like the provided example file.

3. Invoke Pandoc to convert the Markdown document to PDF and apply the filter along the way:

   $ pandoc example.md --filter pandoc-unicode-math -o example.pdf
   

But my keyboard has no "α" and "∃" keys!

The pandoc-unicode-math filter will not make writing math expressions easier. It only makes reading them easier. How to input Unicode symbols depends on your editor. In Vim, digraphs and the characterize plugin are very useful for working with Unicode.

However, to help you get started with existing documents a second filter called pandoc-unicode-math-from-latex is provided that replaces "regular" Latex math commands like \forall or \alpha by equivalent Unicode symbols like ∀ or α. Yes, that means it's the inverse of the pandoc-unicode-math filter, except that pandoc-unicode-math replaces characters like Α (greek Alpha) by A (latin A) but pandoc-unicode-math-from-latex does not do the reverse since this would be ambiguous. This filter can be used like this:

$ pandoc latex-math.md --filter pandoc-unicode-math-from-latex -o unicode-math.md

Limitations

For more complex math containing fractions like \frac{2}{3+5} or lots of subscripts and superscripts like k_{n+1}^2 you still need raw Latex because these things cannot be expressed by single Unicode characters. However, Unicode symbols and Latex commands can be used together in the same expression:

∃ x ∈ ℕ : \frac{x}{2} = 21

Alternatives

Instead of writing Unicode symbols in your source file and applying this filter, you can write regular Latex math commands and use an editor that displays them in a more readable way. For example, using Vim and the Markdown plugin, these settings have the desired effect:

let g:vim_markdown_math=1
set conceallevel=2

Building from source

These filters are written in Haskell, so you need GHC (compiler) and Cabal (build tool), best installed with ghcup if you use a Unix-like OS. You also need the pkg-config tool and the PCRE library (these are required by one of the used Haskell libraries, namely the pcre-heavy package).

Clone the Git repository, change to its top level directory and run the following commands:

$ cabal build
$ cabal install

On Linux, this will install two filters, pandoc-unicode-math and pandoc-unicode-math-from-latex to ~/.cabal/bin/ and on Windows, well, I don't know but surely somewhere sensible.

Contributing

Pull Requests are welcome. It's easy to add new symbols to the src/Symbols.hs file.