Issue838

[brianhuffman]

Make Cryptol REPL accept input lines containing only comments.

Fixes #838.

[yav]

• We could probably remove the %name letDecl entry point to the parser as the repl?
• Maybe add a comment to repl that this is not a part of the language, but rather it is used by the repl (the name is quite suggestive, of course :-)

[brianhuffman]

As for %name letDecl: This, and the parseLetDecl and parseLetDeclWith functions, are part of the cryptol-as-a-library API; even if we're not using these internally for the cryptol REPL, they might be useful to other packages that use cryptol.

[yav]

Is it though? That API is not written down anywhere. If you know that one of our tools is using it, let's keep it by all means. Otherwise, I think we should remove it as this is really not part of Cryptol the language, it just happens to be the notation we use on the text REPL (ideally it should be in a separate parser, but I don't think that happy has support for modularity...)

[brianhuffman]

I just did a search, and it appears that parseLetDecl is not used anywhere in saw-script or any of its dependencies. So it should be safe to remove it. But that's not directly related to this PR, so let's do it in a separate one.