Comment by munificent

I believe you can blame Ken Thompson for this. In DMR's paper about early C history, he says:

> Other fiddles in the transition from BCPL to B were introduced as a matter of taste, and some remain controversial, for example the decision to use the single character = for assignment instead of :=.

I think Ken did most of the early design of B and DMR came along later to help with C. Ken has a famously terse style, so I can definitely see it being on brand to shave of a character from `:=`, which is what BCPL uses.

It's sort of a tricky little syntax problem. It makes perfect sense to use `=` for declarations:

    int x = 1;

At that point, you really are defining a thing, and `=` is the natural syntax for a definition. (It's what BCPL uses for defining most named things.)

You also need a syntax for mutating assignment. You can define a separate operator for that (like `:=`). Then there is the question of equality. From math, `=` is the natural notation because the operator there is often overloaded as an equality predicate.

Now you're in a funny spot. Declaring a variable and assigning to it later are semantically very similar operations. Both ultimately calculate a value and store it in memory. But they have different syntax. Meanwhile, defining a variable and testing two expressions for equality use the same syntax but have utterly unrelated semantics.

Given that math notation has grown chaotically over hundreds of years, it's just really hard to build an elegant notation that is both familiar to people and consistent and coherent.