This is very interesting. Input is a family of fonts designed expressly for writing code by David Jonathan Ross. The full family includes both monospaced and proportional fonts in a variety of widths, weights, and styles all optimized to improve the coding experience.

Unlike most proportional designs, these fonts adopt the helpful attributes of a monospaced design—generous spacing, large punctuation, easily distinguishable characters—while allowing each character to take up the space that it needs.

The proportional styles provide a more comfortable alternative to the monospaced fonts used for everything from text composition to correspondence to code. The capitals get wider so they can feel at home with the lowercase. The Bold weight gets wider so it can feel at home with the Regular. The Condensed styles can work together alongside the Normal width, and the Serif can provide an alternative texture to the Sans.

The typeface’s marketing page includes a useful live preview of the font with real code. The full family is available for US$200 from The Font Bureau.