How to tell alltt not to skip lines at beginning/end?

Question

It seems like there is no option for specifying that, like a hack for verbatim I found on tex.stackexchange:

\usepackage{etoolbox}%
\makeatletter
\preto{\@verbatim}{\topsep=0pt \partopsep=0pt}
\makeatother

\begin{alltt} skips a line before en after its content, how can I remove this ? I tried to use the code below with @alltt instead of @verbatim but it doesn't work.

Indeed I am using knitr which places code input in alltt environment, there may be some other knitr specific solutions too I might be interested in.

MWE:

\documentclass[10pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{alltt}
\usepackage{etoolbox}%

\begin{document}

Few words
\begin{alltt}
alltt words
\end{alltt}
something else

\begin{verbatim}
verbatim words
\end{verbatim}
and with the hack:

\makeatletter
\preto{\@verbatim}{\topsep=0pt \partopsep=0pt}
\makeatother

\begin{verbatim}
verbatim words
\end{verbatim}
the end

\end{document}

Answer 1

There is no \@alltt but like verbatim (and most latex display constructs) alltt is a trivlist so the same settings apply, you just need

\preto{\alltt}{\topsep=0pt \partopsep=0pt}