Hi Stephen, Hi Kevin,
Kevin's right, it's an easy way to get a curved line:
\version "2.18.2"
\markup {
%% your example:
\draw-line #'(1 . 1)
%% your example in path mode:
\path #0.1 #'((moveto 0 0)(curveto 0 0 0 0 1 1))
%% concave example:
\path #0.1 #'((moveto 0 0)(curveto 0 0 1 0 1 1))
%% convex example:
\path #0.1 #'((moveto 0 0)(curveto 0 0 0 1 1 1))
%% more concave example:
\path #0.1 #'((moveto 0 0)(curveto 0 0 2 -1 1 1))
%% more convex example:
\path #0.1 #'((moveto 0 0)(curveto 0 0 -1 2 1 1))
}