diff --git a/Project.toml b/Project.toml
index ce84fa85c..b7663da4d 100644
--- a/Project.toml
+++ b/Project.toml
@@ -34,7 +34,7 @@ StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 [compat]
 CategoricalArrays = "0.5"
 Colors = "0.9"
-Compat = "2"
+Compat = "2.1"
 Compose = "0.7"
 Contour = "0.5"
 CoupledFields = "0.1"
diff --git a/src/Gadfly.jl b/src/Gadfly.jl
index b517bc2af..06edc7630 100755
--- a/src/Gadfly.jl
+++ b/src/Gadfly.jl
@@ -503,7 +503,7 @@ function render_prepare(plot::Plot)
 
     unscaled_aesthetics = setdiff(used_aesthetics, scaled_aesthetics)
 
-    _theme(plt, lyr) = lyr.theme == nothing ? plt.theme : lyr.theme
+    _theme(plt, lyr) = lyr.theme === nothing ? plt.theme : lyr.theme
 
     # Add default scales for statistics.
     layer_stats_with_theme = map(plot.layers, layer_stats) do l, stats
@@ -532,17 +532,17 @@ function render_prepare(plot::Plot)
         in(var, mapped_aesthetics) || continue
 
         var_data = getfield(plot.data, var)
-        if var_data == nothing
+        if var_data === nothing
             for data in datas
                 var_layer_data = getfield(data, var)
-                if var_layer_data != nothing
+                if var_layer_data !== nothing
                     var_data = var_layer_data
                     break
                 end
             end
         end
 
-        var_data == nothing && continue
+        var_data === nothing && continue
 
         t = classify_data(var_data)
         if scale_exists(t, var)
@@ -560,7 +560,7 @@ function render_prepare(plot::Plot)
         t = :categorical
         for data in Iterators.flatten((datas, subplot_datas))
             val = getfield(data, var)
-            if val != nothing && val != :categorical
+            if val !== nothing && val != :categorical
                 t = classify_data(val)
             end
         end
@@ -653,30 +653,33 @@ function render_prepare(plot::Plot)
 
     # I. Scales
     layer_aess = Scale.apply_scales(IterTools.distinct(values(scales)),
-                                    datas..., subplot_datas...)
+                                    vcat(datas, subplot_datas))
 
     # set defaults for key titles
     keyvars = [:color, :shape]
     for (i, layer) in enumerate(plot.layers)
         for kv in keyvars
-            fflag = (getfield(layer_aess[i], Symbol(kv,"_key_title")) == nothing) && haskey(layer.mapping, kv) && !isa(layer.mapping[kv], AbstractArray)
+            fflag = (getfield(layer_aess[i], Symbol(kv,"_key_title")) === nothing) &&
+                haskey(layer.mapping, kv) &&
+                !isa(layer.mapping[kv], AbstractArray)
             fflag && setfield!(layer_aess[i], Symbol(kv,"_key_title"), string(layer.mapping[kv]))
         end
     end
 
     for kv in keyvars
-        fflag = (getfield(layer_aess[1], Symbol(kv,"_key_title")) == nothing) && haskey(plot.mapping, kv) && !isa(plot.mapping[kv], AbstractArray)
+        fflag = (getfield(layer_aess[1], Symbol(kv,"_key_title")) === nothing) &&
+            haskey(plot.mapping, kv) && !isa(plot.mapping[kv], AbstractArray)
         fflag && setfield!(layer_aess[1], Symbol(kv,"_key_title"), string(plot.mapping[kv]))
     end
 
     # Auto-update color scale if shape==color
     catdatas = vcat(datas, subplot_datas)
     shapev = getfield.(catdatas, :shape)
-    di = (shapev.!=nothing) .& (shapev.== getfield.(catdatas, :color))
+    di = @. (shapev !== nothing) & (shapev == getfield(catdatas, :color))
 
     supress_colorkey = false
     for (aes, data) in zip(layer_aess[di], catdatas[di])
-        aes.shape_key_title==nothing && (aes.shape_key_title=aes.color_key_title="Shape")
+        aes.shape_key_title === nothing && (aes.shape_key_title=aes.color_key_title="Shape")
         colorf = scales[:color].f
         scales[:color] =  Scale.color_discrete(colorf, levels=scales[:shape].levels, order=scales[:shape].order)
         Scale.apply_scale(scales[:color], [aes], Gadfly.Data(color=getfield(data,:color))  )
@@ -692,7 +695,7 @@ function render_prepare(plot::Plot)
     end
 
     # IIb. Plot-wise Statistics
-    plot_aes = concat(layer_aess...)
+    plot_aes = concat(layer_aess)
     statistics = collect(statistics)
     Stat.apply_statistics(statistics, scales, coord, plot_aes)
 
@@ -713,7 +716,7 @@ function render_prepare(plot::Plot)
 
     if !supress_keys
         for (KT, kv) in zip(keytypes, keyvars)
-            fflag = !all([getfield(aes, kv)==nothing for aes in [plot_aes, layer_aess...]])
+            fflag = !all([getfield(aes, kv) === nothing for aes in [plot_aes, layer_aess...]])
             fflag && !in(KT, explicit_guide_types) &&  push!(guides, KT())
         end
     end
@@ -756,7 +759,7 @@ function render(plot::Plot)
 
     ctx =  pad_inner(root_context, plot.theme.plot_padding...)
 
-    if plot.theme.background_color != nothing
+    if plot.theme.background_color !== nothing
         compose!(ctx, (context(order=-1000000),
                         fill(plot.theme.background_color),
                         stroke(nothing), rectangle()))
@@ -809,28 +812,24 @@ function render_prepared(plot::Plot,
     # IV. Geometries
     themes = Theme[layer.theme === nothing ? plot.theme : layer.theme
                    for layer in plot.layers]
-    zips = trim_zip(plot.layers, layer_aess,
-                                                   layer_subplot_aess,
-                                                   layer_subplot_datas,
-               themes)
-
-    compose!(plot_context,
-             [compose(context(order=layer.order), render(layer.geom, theme, aes,
-                                                         subplot_aes, subplot_data,
-                                                         scales))
-              for (layer, aes, subplot_aes, subplot_data, theme) in zips]...)
+    zips = trim_zip(plot.layers, layer_aess, layer_subplot_aess,
+                    layer_subplot_datas, themes)
+    for (layer, aes, subplot_aes, subplot_data, theme) in zips
+        r = render(layer.geom, theme, aes, subplot_aes, subplot_data, scales)
+        compose!(plot_context, (context(order=layer.order), r))
+    end#for
 
     # V. Guides
-    guide_contexts = Any[]
+    guide_contexts = Guide.PositionedGuide[]
     for guide in guides
         guide_context = render(guide, plot.theme, plot_aes, dynamic)
-        if guide_context != nothing
+        if guide_context !== nothing
             append!(guide_contexts, guide_context)
         end
     end
 
     tbl = Guide.layout_guides(plot_context, coord,
-                              plot.theme, guide_contexts...)
+                              plot.theme, guide_contexts)
     if table_only
         return tbl
     end
diff --git a/src/aesthetics.jl b/src/aesthetics.jl
index 0ac515231..2617831a1 100755
--- a/src/aesthetics.jl
+++ b/src/aesthetics.jl
@@ -102,7 +102,7 @@ function show(io::IO, data::Aesthetics)
     print(io, "Aesthetics(")
     for name in valid_aesthetics
         val = getfield(data, name)
-        if !ismissing(val) && val != nothing
+        if !ismissing(val) && val !== nothing
             print(io, "\n  ", string(name), "=")
             show(io, getfield(data, name))
         end
@@ -172,7 +172,7 @@ function assert_aesthetics_undefined(who::AbstractString, aes::Aesthetics, vars:
 end
 
 function assert_aesthetics_equal_length(who::AbstractString, aes::Aesthetics, vars::Symbol...)
-    defined_vars = Compat.Iterators.filter(var -> !(getfield(aes, var) === nothing), vars)
+    defined_vars = Compat.Iterators.filter(var -> getfield(aes, var) !== nothing, vars)
 
     if !isempty(defined_vars)
         n = length(getfield(aes, first(defined_vars)))
@@ -198,7 +198,7 @@ end
 #
 function update!(a::Aesthetics, b::Aesthetics)
     for name in valid_aesthetics
-        issomething(getfield(b, name)) && setfield(a, name, getfield(b, name))
+        getfield(b, name) !== nothing && setfield(a, name, getfield(b, name))
     end
     nothing
 end
@@ -226,26 +226,21 @@ json(a::Aesthetics) = join([string(a, ":", json(getfield(a, var))) for var in ae
 # Returns:
 #   A new Aesthetics instance with vectors concatenated.
 #
-function concat(aess::Aesthetics...)
+function concat(aess)
     cataes = Aesthetics()
     for aes in aess
         for var in valid_aesthetics
-            if var in [:xviewmin, :yviewmin]
-                mu, mv = getfield(cataes, var), getfield(aes, var)
-                setfield!(cataes, var,
-                          mu === nothing ? mv :
-                             mv == nothing ? mu :
-                                 min(mu, mv))
-            elseif var in [:xviewmax, :yviewmax]
-                mu, mv = getfield(cataes, var), getfield(aes, var)
-                setfield!(cataes, var,
-                          mu === nothing ? mv :
-                             mv == nothing ? mu :
-                                 max(mu, mv))
+            mu, mv = getfield(cataes, var), getfield(aes, var)
+            isviewmin = var in (:xviewmin, :yviewmin)
+            isviewmax = var in (:xviewmax, :yviewmax)
+            mumv = if isviewmin
+                mu === nothing ? mv : mv === nothing ? mu : min(mu, mv)
+            elseif isviewmax
+                mu === nothing ? mv : mv === nothing ? mu : max(mu, mv)
             else
-                setfield!(cataes, var,
-                          cat_aes_var!(getfield(cataes, var), getfield(aes, var)))
-            end
+                cat_aes_var!(mu, mv)
+            end#if
+            setfield!(cataes, var, mumv)
         end
     end
     cataes
@@ -405,12 +400,12 @@ function inherit!(a::Aesthetics, b::Aesthetics;
         bval = getfield(b, field)
         if field in clobber_set
             setfield!(a, field, bval)
-        elseif aval === missing || aval === nothing || aval === string || aval == showoff
+        elseif aval === missing || aval === nothing || aval === string || aval === showoff
             setfield!(a, field, bval)
-        elseif field == :xviewmin || field == :yviewmin
-            bval != nothing && (aval == nothing || aval > bval) && setfield!(a, field, bval)
-        elseif field == :xviewmax || field == :yviewmax
-            bval != nothing && (aval == nothing || aval < bval) && setfield!(a, field, bval)
+        elseif field in (:xviewmin, :yviewmin) && bval !== nothing
+            (aval === nothing || aval > bval) && setfield!(a, field, bval)
+        elseif field in (:xviewmax, :yviewmax) && bval !== nothing
+            (aval === nothing || aval < bval) && setfield!(a, field, bval)
         elseif typeof(aval) <: Dict && typeof(bval) <: Dict
             merge!(aval, getfield(b, field))
         end
diff --git a/src/coord.jl b/src/coord.jl
index 5358591a1..9d3c1784a 100644
--- a/src/coord.jl
+++ b/src/coord.jl
@@ -153,7 +153,7 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
 
     xmin = xmax = first_concrete_aesthetic_value(aess, coord.xvars)
 
-    if xmin != nothing
+    if xmin !== nothing
         for var in coord.xvars
             for aes in aess
                 vals = getfield(aes, var)
@@ -169,7 +169,7 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
     end
 
     ymin = ymax = first_concrete_aesthetic_value(aess, coord.yvars)
-    if ymin != nothing
+    if ymin !== nothing
         for var in coord.yvars
             for aes in aess
                 vals = getfield(aes, var)
@@ -196,19 +196,19 @@ function apply_coordinate(coord::Cartesian, aess::Vector{Gadfly.Aesthetics},
 
     # viewmin/max that is set explicitly should override min/max
     for aes in aess
-        if aes.xviewmin != nothing
+        if aes.xviewmin !== nothing
             xviewmin = xviewmin === nothing ? aes.xviewmin : min(xviewmin, aes.xviewmin)
         end
 
-        if aes.xviewmax != nothing
+        if aes.xviewmax !== nothing
             xviewmax = xviewmax === nothing ? aes.xviewmax : max(xviewmax, aes.xviewmax)
         end
 
-        if aes.yviewmin != nothing
+        if aes.yviewmin !== nothing
             yviewmin = yviewmin === nothing ? aes.yviewmin : min(yviewmin, aes.yviewmin)
         end
 
-        if aes.yviewmax != nothing
+        if aes.yviewmax !== nothing
             yviewmax = yviewmax === nothing ? aes.yviewmax : max(yviewmax, aes.yviewmax)
         end
     end
diff --git a/src/data.jl b/src/data.jl
index d8334b016..4c63cae71 100644
--- a/src/data.jl
+++ b/src/data.jl
@@ -62,7 +62,7 @@ function chain(ds::Data...)
     chained_data = Data()
     for name in data_fields
         vs = Any[getfield(d, name) for d in ds]
-        vs = Any[v for v in filter(issomething, vs)]
+        vs = Any[v for v in filter(!isnothing, vs)]
         if isempty(vs)
             setfield!(chained_data, name, nothing)
         else
@@ -78,7 +78,7 @@ function show(io::IO, data::Data)
     maxlen = 0
     print(io, "Data(")
     for name in data_fields
-        if getfield(data, name) != nothing
+        if getfield(data, name) !== nothing
             print(io, "\n  ", string(name), "=")
             show(io, getfield(data, name))
         end
diff --git a/src/dataframes.jl b/src/dataframes.jl
index 622237fd4..eeb4e76ba 100644
--- a/src/dataframes.jl
+++ b/src/dataframes.jl
@@ -11,7 +11,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
     vm = um
     grouped_columns = Set{Symbol}()
     for colgroup in colgroups
-        if colgroup.columns===nothing # null => group all columns
+        if colgroup.columns === nothing # null => group all columns
             vm *= un
             grouped_columns = copy(allcolumns)
         else
@@ -34,7 +34,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
 
     # allocate vectors for grouped columns
     for (j, colgroup) in enumerate(colgroups)
-        cols = colgroup.columns===nothing ? allcolumns : colgroup.columns
+        cols = colgroup.columns === nothing ? allcolumns : colgroup.columns
 
         # figure the grouped common column type
         firstcol = U[first(cols)]
@@ -64,7 +64,7 @@ function meltdata(U::AbstractDataFrame, colgroups_::Vector{Col.GroupedColumn})
     col_indicators = Array{Symbol}(undef, vm, length(colgroups))
     row_indicators = Array{Int}(undef, vm, length(colgroups))
 
-    colidxs = [colgroup.columns===nothing ? collect(allcolumns) : colgroup.columns
+    colidxs = [colgroup.columns === nothing ? collect(allcolumns) : colgroup.columns
                for colgroup in colgroups]
 
     vi = 1
diff --git a/src/geom/boxplot.jl b/src/geom/boxplot.jl
index 0fc6222f2..c56a8bcb4 100644
--- a/src/geom/boxplot.jl
+++ b/src/geom/boxplot.jl
@@ -123,7 +123,7 @@ function render(geom::BoxplotGeometry, theme::Gadfly.Theme, aes::Gadfly.Aestheti
         svgclass("geometry"))
 
     # Outliers
-    if !geom.suppress_outliers && aes.outliers != nothing && !isempty(aes.outliers)
+    if !geom.suppress_outliers && aes.outliers !== nothing && !isempty(aes.outliers)
         xys = collect(Iterators.flatten(zip(cycle([x]), ys, cycle([c]))
                              for (x, ys, c) in zip(xs, aes.outliers, cs)))
         compose!(ctx, (context(),
@@ -133,7 +133,7 @@ function render(geom::BoxplotGeometry, theme::Gadfly.Theme, aes::Gadfly.Aestheti
     end
 
     # Middle
-    if aes.middle != nothing
+    if aes.middle !== nothing
         compose!(ctx, (
            context(order=1),
            Compose.line([[(x - fw/2, mid), (x + fw/2, mid)]
diff --git a/src/geom/errorbar.jl b/src/geom/errorbar.jl
index 65dafa47b..2e5bfb4a0 100644
--- a/src/geom/errorbar.jl
+++ b/src/geom/errorbar.jl
@@ -110,7 +110,7 @@ function render(geom::YErrorBarGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthe
         stroke([theme.stroke_color(c) for c in aes.color]),
         linewidth(theme.line_width))
 
-    (aes.color_key_continuous == true || aes.color == nothing) || compose!(ctx,
+    (aes.color_key_continuous == true || aes.color === nothing) || compose!(ctx,
             svgclass([svg_color_class_from_label(aes.color_label([c])[1]) for c in aes.color]))
 
     return ctx
@@ -148,7 +148,7 @@ function render(geom::XErrorBarGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthe
         stroke([theme.stroke_color(c) for c in aes.color]),
         linewidth(theme.line_width))
 
-    (aes.color_key_continuous == true || aes.color == nothing) || compose!(ctx,
+    (aes.color_key_continuous == true || aes.color === nothing) || compose!(ctx,
             svgclass([svg_color_class_from_label(aes.color_label([c])[1])
                       for c in aes.color]))
 
diff --git a/src/geom/hvabline.jl b/src/geom/hvabline.jl
index 70f5248a1..ca8e86000 100755
--- a/src/geom/hvabline.jl
+++ b/src/geom/hvabline.jl
@@ -131,12 +131,12 @@ const abline = ABLineGeometry
 element_aesthetics(geom::ABLineGeometry) = [:intercept, :slope]
 
 function render(geom::ABLineGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics)
-    if aes.intercept == nothing && aes.slope == nothing
+    if aes.intercept === nothing && aes.slope === nothing
         aes.intercept = [0]
         aes.slope = [1]
-    elseif aes.intercept == nothing
+    elseif aes.intercept === nothing
         aes.intercept = fill(0,length(aes.slope))
-    elseif aes.slope == nothing
+    elseif aes.slope === nothing
         aes.slope = fill(1,length(aes.intercept))
     end
     Gadfly.assert_aesthetics_equal_length("Geom.line", aes, element_aesthetics(geom)...)
diff --git a/src/geom/label.jl b/src/geom/label.jl
index a26ee82e7..94a277c60 100644
--- a/src/geom/label.jl
+++ b/src/geom/label.jl
@@ -50,7 +50,7 @@ function deferred_label_context(geom::LabelGeometry,
 
     num_labels = length(aes.label)
 
-    if aes.size == nothing
+    if aes.size === nothing
         padding = fill(theme.point_size, num_labels) .+ theme.label_padding
     else
         padding = aes.size .+ theme.label_padding
@@ -279,7 +279,7 @@ function render(geom::LabelGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics
         end
 
         hpos, vpos, xoff, yoff = label_layouts[geom.position]
-        if aes.size == nothing
+        if aes.size === nothing
             offsets = [(xoff*(theme.point_size + theme.label_padding),
                         yoff*(theme.point_size + theme.label_padding))]
         else
diff --git a/src/geom/point.jl b/src/geom/point.jl
index dd35ab2a0..a98e4fc95 100644
--- a/src/geom/point.jl
+++ b/src/geom/point.jl
@@ -67,7 +67,7 @@ function render(geom::PointGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics
     for (x, y, color, size, shape, alpha) in Compose.cyclezip(aes.x, aes.y, aes.color, aes.size, aes.shape, aes_alpha)
         shapefun = typeof(shape) <: Function ? shape : theme.point_shapes[shape]
         sizeval = typeof(size) <: Int ? interpolate_size(size) : size
-        strokecolor = aes.color_key_continuous != nothing && aes.color_key_continuous ?
+        strokecolor = aes.color_key_continuous !== nothing && aes.color_key_continuous ?
                     theme.continuous_highlight_color(color) :
                     theme.discrete_highlight_color(color)
         class = svg_color_class_from_label(aes.color_label([color])[1])
diff --git a/src/geom/rectbin.jl b/src/geom/rectbin.jl
index 9b64363ff..8a2ae0c81 100644
--- a/src/geom/rectbin.jl
+++ b/src/geom/rectbin.jl
@@ -94,14 +94,14 @@ function render(geom::RectangularBinGeometry, theme::Gadfly.Theme, aes::Gadfly.A
 
     allvisible = true
     for c in cs
-        if c == nothing
+        if c === nothing
             allvisible = false
             break
         end
     end
 
     if !allvisible
-        visibility = cs .!= nothing
+        visibility = (!isnothing).(cs)
         cs = cs[visibility]
         xmin = xmin[visibility]
         xmax = xmax[visibility]
diff --git a/src/geom/segment.jl b/src/geom/segment.jl
index 499763686..a7fc70ae7 100755
--- a/src/geom/segment.jl
+++ b/src/geom/segment.jl
@@ -82,7 +82,7 @@ function render(geom::SegmentGeometry, theme::Gadfly.Theme, aes::Gadfly.Aestheti
 
     if geom.arrow
         check = [aes.xviewmin, aes.xviewmax, aes.yviewmin, aes.yviewmax ]
-        if any( map(x -> x === nothing, check) )
+        if any(map(isnothing, check))
             error("For Geom.vector, Scale minvalue and maxvalue must be manually provided for both axes")
         end
          xyrange = [aes.xviewmax-aes.xviewmin, aes.yviewmax-aes.yviewmin]
diff --git a/src/geom/subplot.jl b/src/geom/subplot.jl
index 08bc4b113..abd4955f7 100644
--- a/src/geom/subplot.jl
+++ b/src/geom/subplot.jl
@@ -144,17 +144,17 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
  # z
     for (layer_data, layer_aes) in zip(subplot_layer_datas, subplot_layer_aess)
         z = getfield(layer_data, :z)
-        (z != nothing) && setfield!(layer_aes, :z, z)
+        (z !== nothing) && setfield!(layer_aes, :z, z)
     end
 
     # work out the grid size
     m = 1
     n = 1
     for layer_aes in subplot_layer_aess
-        if layer_aes.xgroup != nothing
+        if layer_aes.xgroup !== nothing
             m = max(m, maximum(layer_aes.xgroup))
         end
-        if layer_aes.ygroup != nothing
+        if layer_aes.ygroup !== nothing
             n = max(n, maximum(layer_aes.ygroup))
         end
     end
@@ -181,7 +181,7 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
                            Gadfly.Aesthetics[layer_aes_grid[k][i, j]
                                              for k in 1:length(geom.layers)],
                            Gadfly.Data[layer_data_grid[k][i, j]
-                                       for k in 1:length(geom.layers)]...)
+                                       for k in 1:length(geom.layers)])
 
         for (k, stats) in enumerate(layer_stats)
             Stat.apply_statistics(stats, scales, coord, layer_aes_grid[k][i, j])
@@ -190,7 +190,7 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
 
     # apply geom-wide statistics
     geom_aes = Gadfly.concat([layer_aes_grid[k][i,j]
-                              for i in 1:n, j in 1:m, k in 1:length(geom.layers)]...)
+                              for i in 1:n, j in 1:m, k in 1:length(geom.layers)])
     geom_stats = Gadfly.StatisticElement[]
 
     has_stat_xticks = false
@@ -220,7 +220,7 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
     if geom.free_x_axis
         for j in 1:m
             col_aes = Gadfly.concat([layer_aes_grid[k][i, j]
-                                     for i in 1:n, k in 1:length(geom.layers)]...)
+                                     for i in 1:n, k in 1:length(geom.layers)])
             Gadfly.inherit!(col_aes, geom_aes)
             Stat.apply_statistic(Stat.xticks(), scales, coord, col_aes)
 
@@ -231,7 +231,7 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
     if geom.free_y_axis
         for i in 1:n
             row_aes = Gadfly.concat([layer_aes_grid[k][i, j]
-                                     for j in 1:m, k in 1:length(geom.layers)]...)
+                                     for j in 1:m, k in 1:length(geom.layers)])
             Gadfly.inherit!(row_aes, geom_aes)
             Stat.apply_statistic(Stat.yticks(), scales, coord, row_aes)
 
@@ -349,7 +349,7 @@ function render(geom::SubplotGrid, theme::Gadfly.Theme,
         # copy over the correct units, since we are reparenting the children
         for u in 1:size(subtbl, 1), v in 1:size(subtbl, 2)
             for child in subtbl[u, v]
-                if child.units===nothing
+                if child.units === nothing
                     child.units = subtbl.units
                 end
             end
diff --git a/src/guide.jl b/src/guide.jl
index 5e13b7c4c..ab64e060f 100644
--- a/src/guide.jl
+++ b/src/guide.jl
@@ -35,7 +35,7 @@ const questionmark = QuestionMark
 
 function render(guide::QuestionMark, theme::Gadfly.Theme,
                 aes::Gadfly.Aesthetics)
-    text_color = theme.background_color == nothing ?
+    text_color = theme.background_color === nothing ?
             colorant"black" : distinguishable_colors(2,theme.background_color)[2]
     text_box = compose!( context(),
         text(1w,0h+2px,"?",hright,vtop),
@@ -64,7 +64,7 @@ const helpscreen = HelpScreen
 
 function render(guide::HelpScreen, theme::Gadfly.Theme,
                 aes::Gadfly.Aesthetics)
-    box_color = theme.background_color == nothing ?
+    box_color = theme.background_color === nothing ?
             colorant"black" : distinguishable_colors(2,theme.background_color)[2]
     text_color = distinguishable_colors(2,box_color)[2]
     text_strings = ["h,j,k,l,arrows,drag to pan",
@@ -104,7 +104,7 @@ const crosshair = CrossHair
 
 function render(guide::CrossHair, theme::Gadfly.Theme,
                 aes::Gadfly.Aesthetics)
-    text_color = theme.background_color == nothing ?
+    text_color = theme.background_color === nothing ?
             colorant"black" : distinguishable_colors(2,theme.background_color)[2]
     text_box = compose!(
         context(),
@@ -262,7 +262,7 @@ function render_discrete_color_key(colors::Vector{C},
                     fill(theme.key_label_color))
 
                 col = compose!(context(xpos, yoff), swatches, swatch_labels)
-                if aes_color_label != nothing
+                if aes_color_label !== nothing
                     classes = [svg_color_class_from_label(aes_color_label([c])[1]) for c in cs]
                     #class_jscalls = ["data(\"color_class\", \"$(c)\")"
                                      #for c in classes]
@@ -408,14 +408,14 @@ function render(guide::ColorKey, theme::Gadfly.Theme,
         guide_title = aes.color_key_title
     end
 
-    if aes.color_key_colors != nothing &&
-       aes.color_key_continuous != nothing &&
+    if aes.color_key_colors !== nothing &&
+       aes.color_key_continuous !== nothing &&
        aes.color_key_continuous
         continuous_guide = true
     end
 
     color_key_labels = aes.color_label(keys(aes.color_key_colors))
-    if !continuous_guide && (guide.labels != nothing)
+    if !continuous_guide && guide.labels !== nothing
         color_key_labels = guide.labels
     end
 
@@ -457,7 +457,7 @@ function render(guide::ColorKey, theme::Gadfly.Theme,
                                          title_width, theme)
     end
 
-    if aes.shape != nothing
+    if aes.shape !== nothing
         # TODO: Draw key for shapes. We need to think about how to make this
         # work. Do we need to optimize number of columns for shape and size
         # keys? I'm guessing it's not worth it.
@@ -469,7 +469,7 @@ function render(guide::ColorKey, theme::Gadfly.Theme,
     end
 
     position = right_guide_position
-    if gpos != nothing
+    if gpos !== nothing
         position = over_guide_position
         ctxs = [compose(context(), (context(gpos[1],gpos[2]), ctxs[1]))]
     elseif theme.key_position == :left
@@ -569,13 +569,13 @@ visibility.  `ticks` can also be an array of locations, or `nothing`.
 const xticks = XTicks
 
 default_statistic(guide::XTicks) =
-    guide.ticks == nothing ? Stat.identity() : Stat.xticks(ticks=guide.ticks)
+    guide.ticks === nothing ? Stat.identity() : Stat.xticks(ticks=guide.ticks)
 
 function render(guide::XTicks, theme::Gadfly.Theme,
                 aes::Gadfly.Aesthetics, dynamic::Bool=true)
-    guide.ticks == nothing && return PositionedGuide[]
+    guide.ticks === nothing && return PositionedGuide[]
 
-    if Gadfly.issomething(aes.xtick)
+    if aes.xtick !== nothing
         ticks = aes.xtick
         tickvisibility = aes.xtickvisible
         scale = aes.xtickscale
@@ -592,7 +592,7 @@ function render(guide::XTicks, theme::Gadfly.Theme,
         scale = Any[]
     end
 
-    if Gadfly.issomething(aes.xgrid)
+    if aes.xgrid !== nothing
         grids = aes.xgrid
         gridvisibility = length(grids) < length(ticks) ?  tickvisibility[2:end] : tickvisibility
     else
@@ -740,7 +740,7 @@ visibility.  `ticks` can also be an array of locations, or `nothing`.
 const yticks = YTicks
 
 function default_statistic(guide::YTicks)
-    if guide.ticks == nothing
+    if guide.ticks === nothing
         return Stat.identity()
     else
         return Stat.yticks(ticks=guide.ticks)
@@ -749,11 +749,11 @@ end
 
 function render(guide::YTicks, theme::Gadfly.Theme,
                 aes::Gadfly.Aesthetics, dynamic::Bool=true)
-    if guide.ticks == nothing
+    if guide.ticks === nothing
         return PositionedGuide[]
     end
 
-    if Gadfly.issomething(aes.ytick)
+    if aes.ytick !== nothing
         ticks = aes.ytick
         tickvisibility = aes.ytickvisible
         scale = aes.ytickscale
@@ -769,7 +769,7 @@ function render(guide::YTicks, theme::Gadfly.Theme,
         scale = Any[]
     end
 
-    if Gadfly.issomething(aes.ygrid)
+    if aes.ygrid !== nothing
         grids = aes.ygrid
         if length(grids) < length(ticks)
             gridvisibility = tickvisibility[2:end]
@@ -1129,7 +1129,7 @@ end
 function layout_guides(plot_context::Context,
                        coord::Gadfly.CoordinateElement,
                        theme::Gadfly.Theme,
-                       positioned_guides::PositionedGuide...)
+                       positioned_guides::Vector{PositionedGuide})
     # Organize guides by position
     guides = DefaultDict(() -> (Tuple{Vector{Context}, Int})[])
     for positioned_guide in positioned_guides
@@ -1160,9 +1160,9 @@ function layout_guides(plot_context::Context,
     aspect_ratio = nothing
     if isa(coord, Gadfly.Coord.cartesian)
         if coord.fixed
-            aspect_ratio = plot_context.units===nothing ? 1.0 :
-                     abs(plot_context.units.width / plot_context.units.height)
-        elseif coord.aspect_ratio != nothing
+            aspect_ratio = (plot_context.units === nothing) ? 1.0 :
+                abs(plot_context.units.width / plot_context.units.height)
+        elseif coord.aspect_ratio !== nothing
             aspect_ratio = coord.aspect_ratio
         end
     end
@@ -1172,7 +1172,7 @@ function layout_guides(plot_context::Context,
     i = 1
     for (ctxs, order) in guides[top_guide_position]
         for ctx in ctxs
-            if ctx.units===nothing && plot_units!==nothing
+            if ctx.units === nothing && plot_units !== nothing
                 ctx.units = UnitBox(plot_units, toppad=0mm, bottompad=0mm)
             end
         end
@@ -1183,7 +1183,7 @@ function layout_guides(plot_context::Context,
     i += 1
     for (ctxs, order) in guides[bottom_guide_position]
         for ctx in ctxs
-            if ctx.units===nothing && plot_units!==nothing
+            if ctx.units === nothing && plot_units !== nothing
                 ctx.units = UnitBox(plot_units, toppad=0mm, bottompad=0mm)
             end
         end
@@ -1195,7 +1195,7 @@ function layout_guides(plot_context::Context,
     j = 1
     for (ctxs, order) in guides[left_guide_position]
         for ctx in ctxs
-            if ctx.units===nothing && plot_units!==nothing
+            if ctx.units === nothing && plot_units !== nothing
                 ctx.units = UnitBox(plot_units, leftpad=0mm, rightpad=0mm)
             end
         end
@@ -1206,7 +1206,7 @@ function layout_guides(plot_context::Context,
     j += 1
     for (ctxs, order) in guides[right_guide_position]
         for ctx in ctxs
-            if ctx.units===nothing && plot_units!==nothing
+            if ctx.units === nothing && plot_units !== nothing
                 ctx.units = UnitBox(plot_units, leftpad=0mm, rightpad=0mm)
             end
         end
diff --git a/src/guide/keys.jl b/src/guide/keys.jl
index ac3943033..f62568d00 100644
--- a/src/guide/keys.jl
+++ b/src/guide/keys.jl
@@ -32,11 +32,11 @@ function Guide.render(guide::Guide.ShapeKey, theme::Gadfly.Theme, aes::Gadfly.Ae
 
     # Aesthetics for keys: shape_key_title, shape_label (Function), shape_key_shapes (AbstractDict)    
     nshapes = length(unique(aes.shape))
-    guide_title = (guide.title!="Shape" || aes.shape_key_title==nothing) ? guide.title : aes.shape_key_title
+    guide_title = (guide.title!="Shape" || aes.shape_key_title === nothing) ? guide.title : aes.shape_key_title
     shape_key_labels = !(guide.labels==[""]) ? guide.labels : aes.shape_label(1:nshapes)
     
     colors = [nothing]
-    if (aes.shape_key_title !=nothing)  && (aes.color_key_title==aes.shape_key_title)
+    if aes.shape_key_title !== nothing  && (aes.color_key_title==aes.shape_key_title)
         colors = collect(keys(aes.color_key_colors))
     end
     
@@ -70,8 +70,8 @@ function render_discrete_key(labels::Vector{String}, title_ctx::Context, title_w
 
     n = max(length(colors), length(shapes))
     shape1 = shapes[1]
-    shapes = (shape1==nothing) ? fill(theme.key_swatch_shape, n) : theme.point_shapes[shapes]
-    (colors[1]==nothing) && (colors = fill((theme.key_swatch_color==nothing) ? theme.default_color : theme.key_swatch_color, n))
+    shapes = shape1 === nothing ? fill(theme.key_swatch_shape, n) : theme.point_shapes[shapes]
+    (colors[1] === nothing) && (colors = fill((theme.key_swatch_color === nothing) ? theme.default_color : theme.key_swatch_color, n))
 
     # only consider layouts with a reasonable number of columns
     maxcols = theme.key_max_columns < 1 ? 1 : theme.key_max_columns
@@ -144,7 +144,7 @@ function render_discrete_key(labels::Vector{String}, title_ctx::Context, title_w
                     fill(theme.key_label_color))
 
                 col = compose!(context(xpos, yoff), swatches, swatch_labels)
-                if aes_color_label != nothing
+                if aes_color_label !== nothing
                     classes = [svg_color_class_from_label(aes_color_label([c])[1]) for c in clrs]
                     #class_jscalls = ["data(\"color_class\", \"$(c)\")" for c in classes]
                     compose!(col,
diff --git a/src/mapping.jl b/src/mapping.jl
index 12d625a58..072f76696 100644
--- a/src/mapping.jl
+++ b/src/mapping.jl
@@ -87,7 +87,7 @@ end
 function meltdata(U::AbstractVector, colgroups_::Vector{Col.GroupedColumn})
     colgroups = Set(colgroups_)
 
-    if length(colgroups) != 1 || first(colgroups).columns!==nothing
+    if length(colgroups) != 1 || first(colgroups).columns !== nothing
         # if every column is of the same length, treat it as a matrix
         if length(Set([length(u for u in U)])) == 1
             return meltdata(cat(U..., dims=2), colgroups_)
@@ -130,7 +130,7 @@ function meltdata(U::AbstractMatrix, colgroups_::Vector{Col.GroupedColumn})
     vm = um
     grouped_columns = BitSet()
     for colgroup in colgroups
-        if colgroup.columns===nothing
+        if colgroup.columns === nothing
             vm *= un
             grouped_columns = copy(allcolumns)
         else
@@ -149,7 +149,7 @@ function meltdata(U::AbstractMatrix, colgroups_::Vector{Col.GroupedColumn})
     col_indicators = Array{Int}(undef, vm, length(colgroups))
     row_indicators = Array{Int}(undef, vm, length(colgroups))
 
-    colidxs = [colgroup.columns===nothing ? collect(allcolumns) : colgroup.columns
+    colidxs = [colgroup.columns === nothing ? collect(allcolumns) : colgroup.columns
                for colgroup in colgroups]
 
     vi = 1
diff --git a/src/misc.jl b/src/misc.jl
index 4a3591600..b1583a9f8 100644
--- a/src/misc.jl
+++ b/src/misc.jl
@@ -188,9 +188,6 @@ function inherit!(a::T, b::T) where T
 end
 
 
-isnothing(u) = u === nothing
-issomething(u) = !isnothing(u)
-
 negate(f) = x -> !f(x)
 
 
diff --git a/src/scale.jl b/src/scale.jl
index 6972591c4..555806bc6 100644
--- a/src/scale.jl
+++ b/src/scale.jl
@@ -19,9 +19,9 @@ include("color_misc.jl")
 iscategorical(scales::Dict{Symbol, Gadfly.ScaleElement}, var::Symbol) =
         haskey(scales, var) && isa(scales[var], DiscreteScale)
 
-function apply_scales(scales, aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+function apply_scales(scales, aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for scale in scales
-        apply_scale(scale, aess, datas...)
+        apply_scale(scale, aess, datas)
     end
 
     for (aes, data) in zip(aess, datas)
@@ -29,9 +29,9 @@ function apply_scales(scales, aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Dat
     end
 end
 
-function apply_scales(scales, datas::Gadfly.Data...)
+function apply_scales(scales, datas::Vector{Gadfly.Data})
     aess = Gadfly.Aesthetics[Gadfly.Aesthetics() for _ in datas]
-    apply_scales(scales, aess, datas...)
+    apply_scales(scales, aess, datas)
     aess
 end
 
@@ -86,7 +86,7 @@ struct ContinuousScale <: Gadfly.ScaleElement
     function ContinuousScale(vars, trans,
                              minvalue, maxvalue, minticks, maxticks,
                              labels, format, scalable)
-        minvalue != nothing && maxvalue != nothing && minvalue > maxvalue &&
+        minvalue !== nothing && maxvalue !== nothing && minvalue > maxvalue &&
                 error("Cannot construct a ContinuousScale with minvalue > maxvalue")
         new(vars, trans, minvalue, maxvalue, minticks, maxticks, labels, format, scalable)
     end
@@ -100,9 +100,9 @@ function ContinuousScale(vars, trans;
 end
 
 function make_labeler(scale::ContinuousScale)
-    if scale.labels != nothing
+    if scale.labels !== nothing
         xs -> [scale.labels(x) for x in xs]
-    elseif scale.format == nothing
+    elseif scale.format === nothing
         scale.trans.label
     else
         xs -> scale.trans.label(xs, scale.format)
@@ -178,9 +178,12 @@ alpha_continuous(; minvalue=0.0, maxvalue=1.0, labels=nothing, format=nothing, m
      ContinuousScale([:alpha], identity_transform, minvalue=minvalue, maxvalue=maxvalue,
                labels=labels, format=format, minticks=minticks, maxticks=maxticks, scalable=scalable)
 
+# Need to wrap Gadfly.Data in array for apply_scale methods
+apply_scale(scale::Gadfly.ScaleElement, aess::Vector{Gadfly.Aesthetics}, data::Gadfly.Data) =
+    apply_scale(scale, aess, Gadfly.Data[data])
 
 function apply_scale(scale::ContinuousScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for (aes, data) in zip(aess, datas)
         for var in scale.vars
             vals = getfield(data, var)
@@ -242,7 +245,7 @@ function apply_scale(scale::ContinuousScale,
             end
         end
 
-        if scale.minvalue != nothing
+        if scale.minvalue !== nothing
             if scale.vars === x_vars
                 aes.xviewmin = scale.trans.f(scale.minvalue)
             elseif scale.vars === y_vars
@@ -250,7 +253,7 @@ function apply_scale(scale::ContinuousScale,
             end
         end
 
-        if scale.maxvalue != nothing
+        if scale.maxvalue !== nothing
             if scale.vars === x_vars
                 aes.xviewmax = scale.trans.f(scale.maxvalue)
             elseif scale.vars === y_vars
@@ -269,7 +272,7 @@ end
 
 
 function discretize(values, levels=nothing, order=nothing, preserve_order=true)
-    if levels == nothing
+    if levels === nothing
         if preserve_order
             levels = OrderedSet()
             for value in values
@@ -283,7 +286,7 @@ function discretize(values, levels=nothing, order=nothing, preserve_order=true)
         da = discretize_make_ia(values, levels)
     end
 
-    if order != nothing
+    if order !== nothing
         return discretize_make_ia(da, da.values[order])
     else
         return da
@@ -363,7 +366,7 @@ alpha_discrete(; labels=nothing, levels=nothing, order=nothing) =
         DiscreteScale([:linestyle], labels=labels, levels=levels, order=order)
 
 
-function apply_scale(scale::DiscreteScale, aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+function apply_scale(scale::DiscreteScale, aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for (aes, data) in zip(aess, datas)
         for var in scale.vars
             label_var = Symbol(var, "_label")
@@ -412,7 +415,7 @@ const color_none = NoneColorScale
 element_aesthetics(scale::NoneColorScale) = [:color]
 
 function apply_scale(scale::NoneColorScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for aes in aess
         aes.color = nothing
     end
@@ -430,7 +433,7 @@ const color_identity = IdentityColorScale
 element_aesthetics(scale::IdentityColorScale) = [:color]
 
 function apply_scale(scale::IdentityColorScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for (aes, data) in zip(aess, datas)
         data.color === nothing && continue
         aes.color = discretize_make_ia(data.color)
@@ -513,7 +516,7 @@ end
 @deprecate discrete_color_manual(colors...; levels=nothing, order=nothing) color_discrete_manual(colors...; levels=levels, order=order)
 
 function apply_scale(scale::DiscreteColorScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     levelset = OrderedSet()
     for (aes, data) in zip(aess, datas)
         data.color === nothing && continue
@@ -524,13 +527,13 @@ function apply_scale(scale::DiscreteColorScale,
         end
     end
 
-    if scale.levels == nothing
+    if scale.levels === nothing
         scale_levels = [levelset...]
         scale.preserve_order || sort!(scale_levels)
     else
         scale_levels = scale.levels
     end
-    scale.order == nothing || permute!(scale_levels, scale.order)
+    scale.order === nothing || permute!(scale_levels, scale.order)
     colors = convert(Vector{RGB{Float32}}, scale.f(length(scale_levels)))
 
     color_map = Dict([(color, string(label))
@@ -621,8 +624,8 @@ const color_continuous_gradient = color_continuous  ### WHY HAVE THIS ALIAS?
 @deprecate continuous_color(;minvalue=nothing, maxvalue=nothing) color_continuous(;minvalue=nothing, maxvalue=nothing)
 
 function apply_scale(scale::ContinuousColorScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
-    cdata = skipmissing(Iterators.flatten(i.color for i in datas if i.color != nothing))
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
+    cdata = skipmissing(Iterators.flatten(i.color for i in datas if i.color !== nothing))
     if !isempty(cdata)
       cmin, cmax = extrema(cdata)
     else
@@ -630,9 +633,9 @@ function apply_scale(scale::ContinuousColorScale,
     end
 
     strict_span = false
-    scale.minvalue != nothing && scale.maxvalue != nothing && (strict_span=true)
-    scale.minvalue != nothing && (cmin=scale.minvalue)
-    scale.maxvalue != nothing && (cmax=scale.maxvalue)
+    scale.minvalue !== nothing && scale.maxvalue !== nothing && (strict_span=true)
+    scale.minvalue !== nothing && (cmin=scale.minvalue)
+    scale.maxvalue !== nothing && (cmax=scale.maxvalue)
 
     cmin, cmax = promote(cmin, cmax)
 
@@ -693,7 +696,7 @@ struct LabelScale <: Gadfly.ScaleElement
 end
 
 function apply_scale(scale::LabelScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for (aes, data) in zip(aess, datas)
         data.label === nothing && continue
         aes.label = discretize(data.label)
@@ -733,7 +736,7 @@ end
 element_aesthetics(scale::IdentityScale) = [scale.var]
 
 function apply_scale(scale::IdentityScale,
-                     aess::Vector{Gadfly.Aesthetics}, datas::Gadfly.Data...)
+                     aess::Vector{Gadfly.Aesthetics}, datas::Vector{Gadfly.Data})
     for (aes, data) in zip(aess, datas)
         getfield(data, scale.var) === nothing && continue
         setfield!(aes, scale.var, getfield(data, scale.var))
diff --git a/src/statistics.jl b/src/statistics.jl
index a55415ea5..49ad28a88 100644
--- a/src/statistics.jl
+++ b/src/statistics.jl
@@ -17,7 +17,7 @@ using LinearAlgebra
 using Random
 
 import Gadfly: Scale, Coord, input_aesthetics, output_aesthetics,
-               default_scales, isconcrete, setfield!, discretize_make_ia, aes2str
+    default_scales, isconcrete, setfield!, discretize_make_ia, aes2str
 import KernelDensity
 # import Distributions: Uniform, Distribution, qqbuild
 import IterTools: distinct
@@ -186,7 +186,7 @@ function apply_statistic(stat::BarStatistic,
 
     iscontinuous = haskey(scales, var) && isa(scales[var], Scale.ContinuousScale)
 
-    if getfield(aes, minvar) == nothing || getfield(aes, maxvar) == nothing
+    if getfield(aes, minvar) === nothing || getfield(aes, maxvar) === nothing
         minvals, maxvals = barminmax(vals, iscontinuous)
 
         setfield!(aes, minvar, minvals)
@@ -194,9 +194,9 @@ function apply_statistic(stat::BarStatistic,
     end
 
     z = zero(eltype(getfield(aes, othervar)))
-    if getfield(aes, viewminvar) == nothing && z < minimum(getfield(aes, othervar))
+    if getfield(aes, viewminvar) === nothing && z < minimum(getfield(aes, othervar))
         setfield!(aes, viewminvar, z)
-    elseif getfield(aes, viewmaxvar) == nothing && z > maximum(getfield(aes, othervar))
+    elseif getfield(aes, viewmaxvar) === nothing && z > maximum(getfield(aes, othervar))
         setfield!(aes, viewmaxvar, z)
     end
 
@@ -249,7 +249,7 @@ function HistogramStatistic(; bincount=nothing,
                               orientation=:vertical,
                               density=false,
                               limits=NamedTuple())
-    if bincount != nothing
+    if bincount !== nothing
         HistogramStatistic(bincount, bincount, position, orientation, density, limits)
     else
         HistogramStatistic(minbincount, maxbincount, position, orientation, density, limits)
@@ -417,7 +417,7 @@ function apply_statistic(stat::HistogramStatistic,
         # See issue #560. Stacked histograms on a non-linear y scale are a strange
         # thing. After some discussion, the least confusing thing is to make the stack
         # partitioned linearly. Here we make that adjustment.
-        if stat.position == :stack && aes.color != nothing
+        if stat.position == :stack && aes.color !== nothing
             # A little trickery to figure out the scale stack height.
             data = Gadfly.Data()
             setfield!(data, othervar, stack_height)
@@ -561,12 +561,12 @@ function Histogram2DStatistic(; xbincount=nothing,
                                 ybincount=nothing,
                                 yminbincount=3,
                                 ymaxbincount=150)
-    if xbincount != nothing
+    if xbincount !== nothing
         xminbincount = xbincount
         xmaxbincount = xbincount
     end
 
-    if ybincount != nothing
+    if ybincount !== nothing
         yminbincount = ybincount
         ymaxbincount = ybincount
     end
@@ -770,7 +770,7 @@ function apply_statistic(stat::TickStatistic,
             error("TickStatistic cannot be applied to subplot coordinates.")
 
     # don't clobber existing ticks
-    getfield(aes, Symbol(stat.axis, "tick")) == nothing || return
+    getfield(aes, Symbol(stat.axis, "tick")) === nothing || return
 
     in_group_var = Symbol(stat.axis, "group")
     minval, maxval = nothing, nothing
@@ -781,11 +781,11 @@ function apply_statistic(stat::TickStatistic,
     for var in in_vars
         categorical && !in(var,[:x,:y]) && continue
         vals = getfield(aes, var)
-        if vals != nothing && eltype(vals) != Function
-            if minval == nothing
+        if vals !== nothing && eltype(vals) != Function
+            if minval === nothing
                 minval = first(vals)
             end
-            if maxval == nothing
+            if maxval === nothing
                 maxval = first(vals)
             end
             T = promote_type(typeof(minval), typeof(maxval))
@@ -824,17 +824,17 @@ function apply_statistic(stat::TickStatistic,
 
     # check the x/yviewmin/max pesudo-aesthetics
     if stat.axis == "x"
-        if aes.xviewmin != nothing
+        if aes.xviewmin !== nothing
             minval = min(minval, aes.xviewmin)
         end
-        if aes.xviewmax != nothing
+        if aes.xviewmax !== nothing
             maxval = max(maxval, aes.xviewmax)
         end
     elseif stat.axis == "y"
-        if aes.yviewmin != nothing
+        if aes.yviewmin !== nothing
             minval = min(minval, aes.yviewmin)
         end
-        if aes.yviewmax != nothing
+        if aes.yviewmax !== nothing
             maxval = max(maxval, aes.yviewmax)
         end
     end
@@ -959,12 +959,12 @@ function minvalmaxval(minval::T, maxval::T, val, s, ds) where T
         maxval = val
     end
 
-    if s != nothing && typeof(s) <: AbstractFloat
+    if s !== nothing && typeof(s) <: AbstractFloat
         minval = min(minval, val - s)::T
         maxval = max(maxval, val + s)::T
     end
 
-    if ds != nothing
+    if ds !== nothing
         minval = min(minval, val - ds)::T
         maxval = max(maxval, val + ds)::T
     end
@@ -999,7 +999,7 @@ function apply_statistic(stat::BoxplotStatistic,
                          coord::Gadfly.CoordinateElement,
                          aes::Gadfly.Aesthetics)
 
-    xflag = aes.x != nothing
+    xflag = aes.x !== nothing
     aes_x = (xflag ? eltype(aes.x) : Int)[]
     if xflag
         aes_x = aes.x
@@ -1007,10 +1007,10 @@ function apply_statistic(stat::BoxplotStatistic,
         aes_x = ones(Int, length(aes.y))
         aes.x_label = x -> fill("", length(x))
     end
-    colorflag = aes.color != nothing
+    colorflag = aes.color !== nothing
     aes_color =  colorflag ? aes.color : fill(nothing, length(aes_x))
                      
-    if aes.y == nothing
+    if aes.y === nothing
         groups = Any[]
         for (x, c) in zip(aes.x, cycle(aes_color))
             push!(groups, (x, c))
@@ -1150,7 +1150,7 @@ function Stat.apply_statistic(stat::SmoothStatistic,
         error("Stat.loess and Stat.lm require that x and y be bound to arrays of plain numbers.")
     end
 
-    colorflag = aes.color != nothing
+    colorflag = aes.color !== nothing
     aes_color =  colorflag ? aes.color : fill(nothing, length(aes.x))
 
     uc = unique(aes_color)
@@ -1308,18 +1308,18 @@ function apply_statistic(stat::StepStatistic,
     p = sortperm(aes.x, alg=MergeSort)
     permute!(aes.x, p)
     permute!(aes.y, p)
-    aes.group != nothing && permute!(aes.group, p)
-    aes.color != nothing && permute!(aes.color, p)
+    aes.group !== nothing && permute!(aes.group, p)
+    aes.color !== nothing && permute!(aes.color, p)
 
-    if aes.group != nothing
+    if aes.group !== nothing
         Gadfly.assert_aesthetics_equal_length("StepStatistic", aes, :x, :group)
         permute!(aes.x, p)
         permute!(aes.y, p)
         permute!(aes.group, p)
-        aes.color != nothing && permute!(aes.color, p)
+        aes.color !== nothing && permute!(aes.color, p)
     end
 
-    if aes.color != nothing
+    if aes.color !== nothing
         Gadfly.assert_aesthetics_equal_length("StepStatistic", aes, :x, :color)
         # TODO: use this when we switch to 0.4
         # sortperm!(p, aes.color, alg=MergeSort, lt=Gadfly.color_isless)
@@ -1327,13 +1327,13 @@ function apply_statistic(stat::StepStatistic,
         permute!(aes.x, p)
         permute!(aes.y, p)
         permute!(aes.color, p)
-        aes.group != nothing && permute!(aes.group, p)
+        aes.group !== nothing && permute!(aes.group, p)
     end
 
     x_step = Array{eltype(aes.x)}(undef, 0)
     y_step = Array{eltype(aes.y)}(undef, 0)
-    color_step = aes.color == nothing ? nothing : Array{eltype(aes.color)}(undef, 0)
-    group_step = aes.group == nothing ? nothing : Array{eltype(aes.group)}(undef, 0)
+    color_step = aes.color === nothing ? nothing : Array{eltype(aes.color)}(undef, 0)
+    group_step = aes.group === nothing ? nothing : Array{eltype(aes.group)}(undef, 0)
 
     i = 1
     i_offset = 1
@@ -1343,17 +1343,17 @@ function apply_statistic(stat::StepStatistic,
 
         (u > length(aes.x) || v > length(aes.y)) && break
 
-        if (aes.color != nothing &&
+        if (aes.color !== nothing &&
              (aes.color[u] != aes.color[i_offset] || aes.color[v] != aes.color[i_offset])) ||
-           (aes.group != nothing &&
+           (aes.group !== nothing &&
              (aes.group[u] != aes.color[i_offset] || aes.color[v] != aes.group[i_offset]))
             i_offset = max(u, v)
             i = 1
         else
             push!(x_step, aes.x[u])
             push!(y_step, aes.y[v])
-            aes.color != nothing && push!(color_step, aes.color[i_offset])
-            aes.group != nothing && push!(group_step, aes.group[i_offset])
+            aes.color !== nothing && push!(color_step, aes.color[i_offset])
+            aes.group !== nothing && push!(group_step, aes.group[i_offset])
             i += 1
         end
     end
@@ -1405,7 +1405,7 @@ function apply_statistic(stat::FunctionStatistic,
     end
 
     # color was bound explicitly
-    if aes.color != nothing
+    if aes.color !== nothing
         func_color = aes.color
         aes.color = Array{eltype(aes.color)}(undef, length(aes.y) * stat.num_samples)
         groups = Array{Int}(undef, length(aes.y) * stat.num_samples)
@@ -1469,11 +1469,11 @@ function apply_statistic(stat::ContourStatistic,
     ys = aes.y === nothing ? nothing : convert(Vector{Float64}, aes.y)
 
     if typeof(aes.z) <: Function
-        if xs == nothing && aes.xmin != nothing && aes.xmax != nothing
+        if xs === nothing && aes.xmin !== nothing && aes.xmax !== nothing
             xs = range(aes.xmin[1], stop=aes.xmax[1], length=stat.samples)
         end
 
-        if ys == nothing && aes.ymin != nothing && aes.ymax != nothing
+        if ys === nothing && aes.ymin !== nothing && aes.ymax !== nothing
             ys = range(aes.ymin[1], stop=aes.ymax[1], length=stat.samples)
         end
 
@@ -1482,10 +1482,10 @@ function apply_statistic(stat::ContourStatistic,
     elseif typeof(aes.z) <: Matrix
         zs = convert(Matrix{Float64}, aes.z)
 
-        if xs == nothing
+        if xs === nothing
             xs = collect(Float64, 1:size(zs)[1])
         end
-        if ys == nothing
+        if ys === nothing
             ys = collect(Float64, 1:size(zs)[2])
         end
         size(zs) != (length(xs), length(ys)) &&
@@ -1634,7 +1634,7 @@ function apply_statistic(stat::ViolinStatistic,
     grouped_color = Dict{Int, Gadfly.ColorOrNothing}(1=>nothing)
     ux = unique(aes.x)
     uxflag = length(ux) < length(aes.x)
-    colorflag = aes.color != nothing
+    colorflag = aes.color !== nothing
 
     uxflag && (grouped_y = Dict(x=>aes.y[aes.x.==x] for x in ux))
 
@@ -1701,7 +1701,7 @@ function minimum_span(vars::Vector{Symbol}, aes::Gadfly.Aesthetics)
             end
         end
 
-        if span == nothing || (dataspan != nothing && dataspan < span)
+        if span === nothing || (dataspan !== nothing && dataspan < span)
             span = dataspan
         end
     end
@@ -1714,7 +1714,7 @@ function apply_statistic(stat::JitterStatistic,
                          coord::Gadfly.CoordinateElement,
                          aes::Gadfly.Aesthetics)
     span = minimum_span(stat.vars, aes)
-    span == nothing && return
+    span === nothing && return
 
     rng = MersenneTwister(stat.seed)
     for var in stat.vars
@@ -1827,8 +1827,8 @@ function apply_statistic(stat::EnumerateStatistic,
                          scales::Dict{Symbol, Gadfly.ScaleElement},
                          coord::Gadfly.CoordinateElement,
                          aes::Gadfly.Aesthetics)
-    has_x = aes.x != nothing
-    has_y = aes.y != nothing
+    has_x = aes.x !== nothing
+    has_y = aes.y !== nothing
 
     if stat.var == :x && !has_x && has_y
         aes.x = collect(1:length(aes.y))
@@ -1873,10 +1873,10 @@ function apply_statistic(stat::VecFieldStatistic,
     ys = aes.y === nothing ? nothing : Float64.(aes.y)
 
     if isa(aes.z, Function)
-        if xs == nothing && aes.xmin != nothing && aes.xmax != nothing
+        if xs === nothing && aes.xmin !== nothing && aes.xmax !== nothing
             xs = range(aes.xmin[1], stop=aes.xmax[1], length=stat.samples)
         end
-        if ys == nothing && aes.ymin != nothing && aes.ymax != nothing
+        if ys === nothing && aes.ymin !== nothing && aes.ymax !== nothing
             ys = range(aes.ymin[1], stop=aes.ymax[1], length=stat.samples)
         end
 
@@ -1885,10 +1885,10 @@ function apply_statistic(stat::VecFieldStatistic,
     elseif isa(aes.z, Matrix)
         zs = Float64.(aes.z)
 
-        if xs == nothing
+        if xs === nothing
             xs = collect(Float64, 1:size(zs)[1])
         end
-        if ys == nothing
+        if ys === nothing
             ys = collect(Float64, 1:size(zs)[2])
         end
         if size(zs) != (length(xs), length(ys))
@@ -1981,8 +1981,8 @@ function apply_statistic(stat::EllipseStatistic,
     aes::Gadfly.Aesthetics)    
 
     Dat = [aes.x aes.y]
-    colorflag = aes.color != nothing
-    groupflag = aes.group != nothing
+    colorflag = aes.color !== nothing
+    groupflag = aes.group !== nothing
     aes_color = colorflag ? aes.color : fill(nothing, length(aes.x)) 
     aes_group = groupflag ? aes.group : fill(nothing, length(aes.x))
     CT, GT = eltype(aes_color), eltype(aes_group)
@@ -2053,7 +2053,7 @@ function apply_statistic(stat::DodgeStatistic,
                             coord::Gadfly.CoordinateElement,
                             aes::Gadfly.Aesthetics)
 
-    aes.color==nothing && return
+    aes.color === nothing && return
     nbars = length(unique(aes.color))
     othervar = (stat.axis == :x) ? :y : :x
     vals = getfield(aes, stat.axis)
diff --git a/src/varset.jl b/src/varset.jl
index 7773a18ce..ce909e502 100644
--- a/src/varset.jl
+++ b/src/varset.jl
@@ -45,7 +45,7 @@ macro varset(name::Symbol, table)
         push!(parameters, Expr(:kw, var, default))
         push!(inherit_parameters, Expr(:kw, var, :(b.$var)))
         if typ==:ColorOrNothing
-            push!(parsed_vars, :($(var)==nothing ? nothing : parse_colorant($(var))))
+            push!(parsed_vars, :($(var) === nothing ? nothing : parse_colorant($(var))))
         else
             push!(parsed_vars, :($(var)))
         end