Kenneth Iverson
Also: Ken Iverson
Designed APL and argued that the right notation is itself a tool of thought.
Kenneth Iverson was a Canadian computer scientist who believed that the right notation is not a side issue but a central tool of thought. He designed APL, a language built from a concise, powerful set of symbols that let an entire algorithm fit on a single line and be taken in as a whole. His Turing Award lecture, Notation as a Tool of Thought, makes the case directly.
The claim — that a good notation can make hard ideas easy and previously unthinkable ideas routine — runs from mathematics through Iverson to the array languages used in finance and data work today. See notation as a tool of thought and the wider topic of languages & paradigms.