Continuation of previous post: Is this a type error?.

I wrote a small lisp-like language. To create a variable in this language you would write:

(define x 1)

in JavaScript, you would write:

const x = 1;

Because define is structurally similar to a function, language handles it in the same manner (but it doesn't evaluate the first argument).

It is possible to write, for example:

(define 1 1)

But this is an error, first argument suppose to be "symbol", not a number. So I added following check:

if (typeof first !== "string") {
  throw new TypeError(
    `"${name}" expects symbol as the first argument, instead got "${first}"`
  );
}

In this language, this considered to be a type error, but in many other languages it would be a syntax error, for example, in JS:

const 1 = 1
// SyntaxError: missing variable name

I can change the code - move this check to the parser, then an error will become syntax error. On the other side if I will add quote and eval to the language I still can get this error (at eval stage):

(eval (quote (define 1 1)))

Just another interesting case of how the same error can be interpreted as a type error or not depending on the point of view.