The 'unit of thought' thing is a nod to the Ken Iverson paper on APL that won him the Turing Award ("Notation as a Tool of Thought"), also referenced by Dyalog'

The 'unit of thought' thing is a nod to the Ken Iverson paper on APL that won him the Turing Award ("Notation as a Tool of Thought"), also referenced by Dyalog's tag line "The tool of thought for software solutions"). Variations of that phrase are endemic in the array languages space.