use [each lt, v] to replace concat(lt, [v])

examples/hollow_out/hollow_torus_knot.scad

@@ -41,7 +41,7 @@ module hollow_out_torus_knot(shape, p, q, phi_step, thickness, line_style) {
                 [0, 90 - a[0], a[1]]
             ]
         )
-       cross_sections(shape, path, concat([angles[0]], angles));
+       cross_sections(shape, path, [angles[0], each angles]);
     
     pts = torus_knot(p, q, phi_step);
     sects = sects_by_path(shape, pts);

examples/maze/torus_knot_maze.scad

@@ -21,7 +21,7 @@ module torus_knot_maze() {
     cell_width = 1;
     torus_knot_path = torus_knot(p, q, phi_step) * rows;
     columns = len(torus_knot_path);
-	path = concat(torus_knot_path, [torus_knot_path[0]]);
+	path = [each torus_knot_path, torus_knot_path[0]];
 
     angle_yz_path = [
 		for(i = [0:len(path) - 2]) 
@@ -34,7 +34,7 @@ module torus_knot_maze() {
 		[90 - phi, theta]
 	];
 	
-	angle_yz = concat(angle_yz_path, [angle_yz_path[0]]);
+	angle_yz = [each angle_yz_path, angle_yz_path[0]];
 
     walls = mz_square_walls(
                 mz_square_cells(rows, columns, x_wrapping = true), 

examples/spiral/vx_spiral_text.scad

@@ -55,7 +55,5 @@ function _px_spiral(from, leng, max_leng, clockwise, dir) =
     leng > max_leng ? [] : _px_spiral_go_turn(from, leng, max_leng, clockwise, dir);
     
 function px_spiral(init_leng, max_leng, clockwise = false) =
-    let(
+    let(org = [0, 0])
-        org = [0, 0]
+    [org, each _px_spiral(org, init_leng, max_leng, clockwise, 0)];
-    )
-    concat([org], _px_spiral(org, init_leng, max_leng, clockwise, 0));

examples/spiral_polygons/spiral_polygons.scad

@@ -24,7 +24,7 @@ module spiral_polygons(beginning_radius, line_width, fn, n) {
 	
 	module drawPolygon(r) {
 	    pts = shape_circle(radius = r, $fn = fn);
-		polyline_join(concat(pts, [pts[0]]))
+		polyline_join([each pts, pts[0]])
 		    circle(half_line_width, $fn = 12);
 	}
 	

examples/spiral_polygons/square_pursuit_3d.scad

@@ -22,7 +22,7 @@ module square_pursuit_3d(length, diff_scale, diameter, n) {
             
             npts = [for(i = [0:3]) inter_p(pts[i], pts[(i + 1) % 4], leng, d)];
             
-            polyline_join(concat(npts, [npts[3], npts[0]]))
+            polyline_join([each npts, npts[3], npts[0]])
 			    sphere(d = diameter);
             
             _square_pursuit_3d(npts, diff_scale, diameter, n - 1);
@@ -37,7 +37,7 @@ module square_pursuit_3d(length, diff_scale, diameter, n) {
         [0, length, 0]
     ];    
     
-    polyline_join(concat(pts, [pts[3], pts[0]]))
+    polyline_join([each pts, pts[3], pts[0]])
 	    sphere(d = diameter);
     
     _square_pursuit_3d(pts, diff_scale, diameter, n - 1);

examples/tiles/tiled_line_ring.scad

@@ -1,5 +1,6 @@
 use <experimental/tile_truchet.scad>;
 use <polyline_join.scad>;
+use <polyhedra/icosahedron.scad>;
 
 radius = 15;
 height = 10;
@@ -12,27 +13,22 @@ module tiled_line_ring(radius, height, line_diameter) {
 	    round(2 * radius * PI / line_diameter), 
 		round(height / line_diameter)
 	];
-    lines = concat(
+    lines = [
-        [
 		for(tile = tile_truchet(size)) 
 		let(
 			x = tile[0],
 			y = tile[1],
 			i = tile[2]
 		)
-            i <= 1 ? 
+		if(i <= 1)  [
-			    [
 			[x * half_line_diameter, y * line_diameter], 
 			[(x + 1) * half_line_diameter, (y + 1) * line_diameter]
 		] 
-				: 
+	    else [
-				[
 			[(x + 1) * half_line_diameter, y * line_diameter],
 			[x * half_line_diameter, (y + 1) * line_diameter]
 		]  
-        ]
+    ];
-    );
-            
             
 	a = 360 / size[0];
     for(line = lines) {
@@ -41,7 +37,7 @@ module tiled_line_ring(radius, height, line_diameter) {
 		        [radius * cos(a * p[0]), radius * sin(a * p[0]), p[1]]
 		];
         polyline_join(pts) 
-		    sphere(half_line_diameter);
+		    icosahedron(half_line_diameter);
     }
 }
 

examples/turtle/hilbert_curve_drawing.scad

@@ -7,11 +7,7 @@ diameter = 0.3;
 corner_r = 0.5;
 
 lines = hilbert_curve();
-hilbert_path = dedup(
+hilbert_path = dedup([each [for(line = lines) line[0]], lines[len(lines) - 1][1]]);
-    concat(
-        [for(line = lines) line[0]], 
-        [lines[len(lines) - 1][1]])
-    );
 smoothed_hilbert_path = bezier_smooth(hilbert_path, corner_r);
 
 polyline_join(smoothed_hilbert_path)

examples/voronoi/voronoi_melon.scad

@@ -14,7 +14,7 @@ module voronoi_melon(eyelets, radius) {
 
     color("DarkKhaki")
 	for(cell = cells) {
-		polyline_join(concat(cell, [cell[0]]))
+		polyline_join([each cell, cell[0]])
 			sphere(radius / 60, $fn = 4);
 	}
 	

examples/voronoi/voronoi_sphere.scad

@@ -60,7 +60,7 @@ module voronoi_sphere(pts, region_hollow, region_offset, region_height) {
 		}
 		
 
-		polyline_join(concat(cell, [cell[0]]))
+		polyline_join([each cell, cell[0]])
 			sphere(region_offset / 2, $fn = 5);
 	}
 }

examples/voronoi/voronoi_vase.scad

@@ -50,7 +50,13 @@ module voronoi_vase(r, h, thickness, num_of_pts, fn, profile_step) {
             intersection() {
                 sweep(sections);
                 render() 
-                    vrn3_from(concat([for(i = indices) pts[i]],  [sections[0][0], sections[0][half_fn], sections[last_section_i][0], sections[last_section_i][half_fn]]));  
+                    vrn3_from([
+                        each [for(i = indices) pts[i]],  
+                        sections[0][0], 
+                        sections[0][half_fn], 
+                        sections[last_section_i][0], 
+                        sections[last_section_i][half_fn]
+                    ]);  
             }
         }