Creating a hybrid mapsto/leadsto arrow

Question

I have a construction that isn't a function, but does produce values assigned (in an ill defined way) varyingly over a domain. I can write this as A \leadsto B. I want to write what happens to a \in A not as a \mapsto b but with a \leadsto arrow that begins with the small vertical bar \mapstochar. I've already loaded the extpfeil package, so stmaryrd won't work. What can I do?

Answer 1

Use \mapstochar and \leadsto, that's simple! With just a small correction for hiding the bump.

\documentclass{article}
\usepackage{amsmath,amssymb}
\begin{document}

$a\mapstochar\mathrel{\mspace{0.45mu}}\leadsto b$

\end{document}

Of course you'll want to define a macro for it:

\newcommand{\foo}{\mapstochar\mathrel{\mspace{0.45mu}}\leadsto}

If you load latexsym rather than amssymb, then more spacing is needed

\documentclass{article}
\usepackage{amsmath,latexsym}
\begin{document}

$a\mapstochar\mathrel{\mspace{1.75mu}}\leadsto b$

\end{document}