Pet peeve here: "variable" and "mutable" aren't concepts that are useful to conflate. Imagine a function that takes a variable and prints its value to the command line. There's no mutation of the variable going on, so the variable is immutable. And yet it's still a variable because each time that you call this function, the value that gets printed is allowed to vary. This is distinct from a constant, where each time you call the function the value of a constant must be the same.

At a quick glance one might mistake var for val since they're only one letter apart. The definitions do make sense though.

I don't find it to be confusing but you'd get more autocomplete help if let was used for constants.

l => let

v => var

The look?