zle -N insert-datestamp _insert_datestamp
bindkey '^t' insert-datestamp
+# prefix search (up to cursor position)
+autoload history-search-end
+zle -N history-beginning-search-backward-end history-search-end
+zle -N history-beginning-search-forward-end history-search-end
+bindkey "\e[5~" history-beginning-search-backward-end # PageUp
+bindkey "\e[6~" history-beginning-search-forward-end # PageDown
+
# vim:ft=zsh