refactor

src/__comm__/_str_hash.scad

@@ -4,5 +4,10 @@ function _str_hash(value) =
 		end = len(chars) - 1
 	)
 	end == 0 ? ord(chars[0]) :
-	let(cum_total = [for(i = 0, s = ord(chars[0]); i < end; i = i + 1, s = s + (ord(chars[i]) * 31 ^ i)) s])
+	let(
+		cum_total = [
+			for(i = 0, s = ord(chars[0]), is_continue = i < end; 
+			    is_continue; 
+				i = i + 1, is_continue = i < end,  s = is_continue ? s + (ord(chars[i]) * 31 ^ i) : undef) s]
+	)
 	cum_total[end - 1] + (ord(chars[end]) * 31 ^ end);

src/experimental/polar_zonohedra.scad

@@ -1,22 +0,0 @@
-use <ptf/ptf_rotate.scad>;
-use <sweep.scad>;
-
-module polar_zonohedra(n){
-    spiral = [
-        for(r=[0:n])
-        let(p = ptf_rotate([10, 0, PI * 10 * r / n], [0, 0, -360 * r / n]) - [10, 0, 0])
-        [p[0], p[1], p[2] * 1.75]
-    ];
-
-    sections = [
-        for(i=[0:n])
-            [for(p = spiral) ptf_rotate(p, [0, 0, 360 * i /  n])]
-    ];
-
-    sweep(sections);
-}
-
-for(n = [4:8]) {
-    translate([50 * (n - 4), 0, 0])
-        polar_zonohedra(n);
-}

src/util/_impl/_shuffle_impl.scad

@@ -3,5 +3,10 @@ use <../swap.scad>;
 function _shuffle(lt, indices, leng) =
     let(end = len(lt) - 1)
     end == 0 ? lt :
-    let(cum = [for(i = 0, s = swap(lt, i, indices[i]); i < end; i = i + 1, s = swap(s, i, indices[i])) s])
+    let(
+        cum = [
+            for(i = 0, s = swap(lt, 0, indices[0]), is_continue = i < end; 
+                is_continue; 
+                i = i + 1, is_continue = i < end, s = is_continue ? swap(s, i, indices[i]) : undef) s]
+    )
     swap(cum[end - 1], end, indices[end]);

src/util/sub_str.scad

@@ -11,6 +11,10 @@
 function sub_str(t, begin, end) = 
     let(
         ed = is_undef(end) ? len(t) : end,
-        cum = [for(i = begin, s = t[i]; i < ed; i = i + 1, s = str(s, t[i])) s]
+        cum = [
+            for(i = begin, s = t[i], is_continue = i < ed; 
+                is_continue; 
+                i = i + 1, is_continue = i < ed, s = is_continue ? str(s, t[i]) : undef) s
+        ]
     )
     cum[len(cum) - 1];

src/util/sum.scad

@@ -11,5 +11,10 @@
 function sum(lt) = 
     let(end = len(lt) - 1)
     end == 0 ? lt[0] :
-    let(cum_total = [for(i = 0, s = lt[0]; i < end; i = i + 1, s = s + lt[i]) s])
+    let(
+        cum_total = [
+            for(i = 0, s = lt[0], is_continue = i < end; 
+                is_continue; 
+                i = i + 1, is_continue = i < end, s = is_continue ? s + lt[i] : undef) s]
+    )
     cum_total[end - 1] + lt[end];