List with arrows instead of bullets

In addition to the provided answers, if you use enumitem package, instead of redefining the label for all your itemize environments, you can define a new arrowlist environment which uses arrows instead of bullets, leaving the standard itemize unnaffected.

\documentclass{article}
\usepackage{enumitem}
\newlist{arrowlist}{itemize}{1}
\setlist[arrowlist]{label=$\Rightarrow$}

\begin{document}

\begin{arrowlist}
\item Line 1
\item Line 2
\end{arrowlist}

\end{document}

I think the question you're linking to is meaning another syntax, but this works :

\documentclass{article}

\begin{document}
\begin{itemize}%[leftmargin=1em]
  \renewcommand{\labelitemi}{$\Rightarrow$}
 \item Line 1
 \item Line 2
\end{itemize}
\end{document}

 \renewcommand\labelitemi{$\Rightarrow$}