Circles at the ends of arrows

Question

Consider four kinds of "arrow" symbols: 0. A horizontal line 1. A leftarrow 2. A rightarrow 3. A doublearrow

I'd like to add circles to each end of these arrows, allowing for all possible combinations of "filled" and "unfilled," for a total of sixteen combinations in total. As an example, one may consider the "spoons" offered by the MnSymbol package for reference, as in \leftspoon and \leftfilledspoon.

Any ideas as to how to achieve this?

EDIT: So to clarify, I want circles on BOTH ends of the arrows. As in O-->O.

Answer 1

You can use \hbox to create your own arrows by appending other symbols, like this:

\def\CircleftarrowCirc{\hbox{$\circ$}\kern-1.5pt\hbox{$\leftarrow$}\kern 1.5pt\hbox{$\circ$}}

Answer 2

I think the intended arrowtips are the following:

which were produced with the following code:

\documentclass{standalone}
\usepackage{tikz}
\begin{document}

\def\generateFourVariants#1{% Parameter, arrow style
\xdef\y{0}
\foreach \left in {white, black} {
  \foreach \right in {white,black} {
    \draw[fill=\left]  (0,\y) circle (2pt);    
    \draw[fill=\right] (1,\y) circle (2pt);
    \draw[shorten <=2pt, shorten >=2pt, arrows=#1] (0,\y) -- (1, \y);
    \pgfmathparse{\y+1}
    \global\let\y\pgfmathresult
  }
 }
}

\begin{tikzpicture}[>=latex]
  \begin{scope}[xshift=0 cm]
  \generateFourVariants{}
  \end{scope}
  \begin{scope}[xshift=2 cm]
  \generateFourVariants{->}
  \end{scope}
  \begin{scope}[xshift=4 cm]
  \generateFourVariants{<-}
  \end{scope}
  \begin{scope}[xshift=6 cm]
  \generateFourVariants{<->}
  \end{scope}

\end{tikzpicture}
\end{document}

But I'm not sure if this answers the OP question...

Answer 3

Package txfonts contains all these symbols, however I am counting nine variants:

\documentclass{article}
\usepackage{txfonts}

\begin{document}
\begin{enumerate}
\item $-$
\item $\multimapinv$, $\multimapdotinv$
\item $\multimap$, $\multimapdot$
\item $\multimapboth$,
      $\multimapdotbothA$, $\multimapdotbothB$
      $\multimapdotboth$
\end{enumerate}
\end{document}