I am writing a small Mathematical expression parser and need a list of all Mathematica build-in Heads (system context?) so I can check the type of input.
Equal, and so on. i.e. those names which return from the command
Head[..]. This does not include user level expressions ofcourse. Only system level
Heads, obtained from Fresh kernel.
I googled and could not find an answer. May be this is something that can be obtained WolframLanguageData ? But I never used this, and when I looked at it, I did not see how to ask it for this.