Actual title is “Humanist 34.54 - punctuation in the assignment statement”, but I changed the title to something reflecting the contents. The original title is because this essay is part of a newsgroup thread which started with that title.
I’d always just assumed that ≔ was one of the many ‘definition’ symbols from the various mathematical traditions, like ≜ or ≝ or even ≡. Unicode contains many variations on this dotted double hyphen; I’m sure all with their own stories.
Smalltalk’s MVC bitmap font faces (early eighties era, as seen in the color books) rendered the ASCII _ as ⭠, meaning assignment. The := digraph was an alias that later supplanted the arrow.
Does anybody know why the caret (^) is used for XOR?
It looks like a logical conjunction…