use for directly

src/matrix/_impl/_m_determinant_impl.scad

@@ -1,11 +1,15 @@
-use <../../util/slice.scad>;
 use <../../util/sum.scad>;
 
 function _m_determinant_sub(matrix, leng, fc) = 
     let(
         init_sub_m = [for(i = [1:leng - 1]) matrix[i]],
         sub_m = [for(i = [0:len(init_sub_m) - 1]) 
-            concat(slice(init_sub_m[i], 0, fc), slice(init_sub_m[i], fc + 1))
+		    let(
+			    mi = init_sub_m[i],
+				leng_mi = len(mi)
+			)
+		    [for(j = 0; j < leng_mi; j = j + 1) if(j != fc) mi[j]]
+            
         ],
         sgn = pow(-1, fc % 2)
     )

src/util/_impl/_dedup_impl.scad

@@ -1,5 +1,3 @@
-
-use <../slice.scad>;
 use <../some.scad>;
 
 function _dedup(elems, leng, buckets, eq, hash, bucket_numbers, i = 0) = 
@@ -15,8 +13,6 @@ function _dedup_add(buckets, i_elem, eq, hash, bucket_numbers) =
 	)
 	some(bucket, function(i_e) eq(i_e[1], elem)) ? buckets : _add(buckets, bucket, i_elem, b_idx);
 
-function _add(buckets, bucket, i_elem, b_idx) = concat(
-	slice(buckets, 0, b_idx), 
-	[concat(bucket, [i_elem])], 
-	slice(buckets, b_idx + 1)
-);
+function _add(buckets, bucket, i_elem, b_idx) = 
+    let(leng = len(buckets))
+	[for(i = 0; i < leng; i = i + 1) i == b_idx ? concat(bucket, [i_elem]) : buckets[i]];

src/util/map/_impl/_hashmap_put_impl.scad

@@ -1,4 +1,3 @@
-use <../../slice.scad>;
 use <../../some.scad>;
 use <../../find_index.scad>;
 
@@ -13,20 +12,12 @@ function _hashmap_put(map, key, value, eq, hash) =
 
 function _replace(map, bucket, key, value, b_idx, k_idx) = 
     let(
-		n_bucket = concat(
-			slice(bucket, 0, k_idx),
-			[[key, value]],
-			slice(bucket, k_idx + 1)
-		)
+	    leng_bucket = len(bucket),
+		n_bucket = [for(i = 0; i < leng_bucket; i = i + 1) i == k_idx ? [key, value] : bucket[i]],
+		leng_map = len(map)
 	)
-	concat(
-		slice(map, 0, b_idx), 
-		[n_bucket], 
-		slice(map, b_idx + 1)
-	);
+	[for(i = 0; i < leng_map; i = i + 1) i == b_idx ? n_bucket : map[i]];
 
-function _put(map, bucket, key, value, b_idx) = concat(
-	slice(map, 0, b_idx), 
-	[concat(bucket, [[key, value]])], 
-	slice(map, b_idx + 1)
-);
+function _put(map, bucket, key, value, b_idx) = 
+    let(leng_map = len(map))
+    [for(i = 0; i < leng_map; i = i + 1) i == b_idx ? concat(bucket, [[key, value]]) : map[i]];

src/util/map/hashmap_del.scad

@@ -9,20 +9,20 @@
 **/
 
 use <../../__comm__/_str_hash.scad>;
-use <../slice.scad>;
 use <../find_index.scad>;
 
 function hashmap_del(map, key, eq = function(e1, e2) e1 == e2, hash = function(e) _str_hash(e)) =
     let(
 	    bidx = hash(key) % len(map),
 		bucket = map[bidx],
-		leng = len(bucket)
+		leng_bucket = len(bucket),
+		leng_map = len(map)
 	)
-	leng == 0 ? map :
+	leng_bucket == 0 ? map :
 	let(i = find_index(bucket, function(e) eq(e[0], key)))
 	i == -1 ? map : 
-	concat(
-	    slice(map, 0, bidx), 
-		[concat(slice(bucket, 0, i), slice(bucket, i + 1))],
-		slice(map, bidx + 1)
-	);
+	[
+	    for(j = 0; j < leng_map; j = j + 1) j == bidx ? 
+	        [for(k = 0; k < leng_bucket; k = k + 1) if(k != i) bucket[k]] :
+			map[j]
+	];

src/util/map/hashmap_get.scad

@@ -9,7 +9,6 @@
 **/
 
 use <../../__comm__/_str_hash.scad>;
-use <../slice.scad>;
 use <../find_index.scad>;
 
 function hashmap_get(map, key, eq = function(e1, e2) e1 == e2, hash = function(e) _str_hash(e)) =

src/util/set/_impl/_hashset_add_impl.scad

@@ -1,4 +1,3 @@
-use <../../slice.scad>;
 use <../../some.scad>;
 
 function _hashset_add(set, elem, eq, hash) =
@@ -8,8 +7,6 @@ function _hashset_add(set, elem, eq, hash) =
 	)
 	some(bucket, function(e) eq(e, elem)) ? set : _add(set, bucket, elem, idx);
 
-function _add(set, bucket, elem, idx) = concat(
-	slice(set, 0, idx), 
-	[concat(bucket, [elem])], 
-	slice(set, idx + 1)
-);
+function _add(set, bucket, elem, idx) = 
+    let(leng = len(set))
+	[for(i = 0; i < leng; i = i + 1) i == idx ? concat(bucket, [elem]) : set[i]];

src/util/set/hashset_del.scad

@@ -9,7 +9,6 @@
 **/
 
 use <../../__comm__/_str_hash.scad>;
-use <../slice.scad>;
 use <../find_index.scad>;
 
 function hashset_del(set, elem, eq = function(e1, e2) e1 == e2, hash = function(e) _str_hash(e)) =