Interesting user mistake

[via Digitalmars-d]

On Thursday, 3 September 2015 at 17:12:31 UTC, H. S. Teoh wrote:
> Is there a way for the lexer to check for the specific 
> character sequence '=', '+', whitespace and not others (e.g. 
> '=', whitespace, '+')?  IOW, "a =+ b" will be prohibited, but 
> "a = + b" will be allowed. If so, I agree with this.
>
> On that note, though, the unary + operator is totally useless 
> in D... maybe we should get rid of that instead?  (Then "=+" 
> will automatically be an error.)

What about the generalization? E.g., '=', '-', whitespace?