create `scale_*` functions

[ernestguevarra]

#' A muted, qualitative color palette
#'
#' @export
#' @examples
#' library(scales)
#' scales::show_col(ipsum_pal()(9))
ipsum_pal <- function() { manual_pal(ipsum_palette) }

#' Discrete color & fill scales based on the ipsum palette
#'
#' See [ipsum_pal()].
#'
#' @md
#' @inheritDotParams ggplot2::discrete_scale -expand -position
#' @rdname scale_ipsum
#' @export
scale_colour_ipsum <- function(...) {
  if (is_3.5()) {
    discrete_scale(aesthetics = "colour", palette = ipsum_pal(), ...)
  } else {
    discrete_scale("colour", "ipsum", ipsum_pal(), ...)
  }
}

#' @export
#' @rdname scale_ipsum
scale_color_ipsum <- scale_colour_ipsum

#' @export
#' @rdname scale_ipsum
scale_fill_ipsum <- function(...) {
  if (is_3.5()) {
    discrete_scale(aesthetics = "fill", palette = ipsum_pal(), ...)
  } else {
    discrete_scale("fill", "ipsum", ipsum_pal(), ...)
  }
}