Damn.

Tony Hoare was on my bucket list of people I wanted to meet before I or they die. My grad school advisor always talked of him extremely highly, and while I cannot seem to confirm it, I believe Hoare might have been his PhD advisor.

It's hard to overstate how important Hoare was. CSP and Hoare Logic and UTP are all basically entire fields in their own right. It makes me sad he's gone.