cairo:line-to (cr x y)

cr -- a cairo:context-t instance
x -- a number for the x coordinate of the end of the new line
y -- a number for the y coordinate of the end of the new line

Adds a line to the path from the current point to position (x,y) in user-space coordinates. After this call the current point will be (x,y).

If there is no current point before the call to the cairo:line-to function this function will behave as:

(cairo:move-to cr x y)  

The numbers for the arguments are coerced to double floats before being passed to the foreign C function.