Awesome
APL language support in Atom
This package adds Atom support for everybody's favourite array-wrangling crypto-language.
Font Support
No APL symbol fonts are bundled with this package. Anybody interested in APL is assumed to already have supporting fonts installed. Furthermore, Windows and Mac OS both ship with fonts that support APL symbols (Arial Unicode MS and Menlo, to name two), so you'll probably be fine.
If the characters aren't displaying correctly, try installing any or all of these:
Side-note: I recommend installing Symbola anyway, even if you think you don't need it. Noto Sans Symbols is highly‑recommended as well. Install them both to dispel tofu!