diff --git a/Dict.ark b/Dict.ark
index 5b755cd..63bde12 100644
--- a/Dict.ark
+++ b/Dict.ark
@@ -99,6 +99,7 @@
 
 # @brief Computes the number of (key, value) pairs in a given dictionary
 # @param _D dictionary
+# @deprecated Use the builtin `len` instead
 # =begin
 # (let data (dict "key" "value"))
 # (print (dict:size data))  # 1
@@ -293,13 +294,12 @@
   (mut _output "[")
   (mut _i 0)
   (while (< _i (len _L)) {
-    (set _output
-      (+
-        _output
-        (_valAsJson (@ _L _i))
-        (if (= (len _L) (+ 1 _i))
-          ""
-          ", ")))
+    (set _output (+
+      _output
+      (_valAsJson (@ _L _i))
+      (if (= (len _L) (+ 1 _i))
+        ""
+        ", ")))
     (set _i (+ 1 _i)) })
 
   (+ _output "]") }))
@@ -327,13 +327,12 @@
   (mut _as_str "")
   (set _i 0)
   (while (< _i (len _output)) {
-    (set _as_str
-      (+
-        _as_str
-        (@ _output _i)
-        (if (= (len _output) (+ 1 _i))
-          ""
-          ", ")))
+    (set _as_str (+
+      _as_str
+      (@ _output _i)
+      (if (= (len _output) (+ 1 _i))
+        ""
+        ", ")))
     (set _i (+ 1 _i)) })
 
   (+ "{" _as_str "}") }))
diff --git a/List.ark b/List.ark
index 409bff6..03867a2 100644
--- a/List.ark
+++ b/List.ark
@@ -61,6 +61,7 @@
 
 # @brief Function to call the `len` operator on a list
 # @param _L list to get the size of
+# @deprecated Use the builtin `len` instead
 # =begin
 # (print (list:size [1 2 3 4]))  # 4
 # =end
diff --git a/Macros.ark b/Macros.ark
index bcfe945..aeeaa0f 100644
--- a/Macros.ark
+++ b/Macros.ark
@@ -1,6 +1,6 @@
 # internal, do not use
 (macro __replace_all_placeholders_with (replacement x ...xs) {
-  ($if (empty? xs)
+  ($if ($empty? xs)
     ($if (= "_" ($repr x))
       replacement
       x)
@@ -26,7 +26,7 @@
   ($if (= "Symbol" ($type fn1))
     (macro call (fn1 arg))
     (macro call ((__replace_all_placeholders_with arg ...fn1))))
-  ($if (> (len fns) 0)
+  ($if (> ($len fns) 0)
     (-> call ...fns)
     call) })
 
@@ -48,11 +48,11 @@
 # =end
 # @author https://github.com/SuperFola
 (macro partial (func ...defargs) {
-  (macro bloc (__suffix-dup a (- ($argcount func) (len defargs))))
+  (macro bloc (__suffix-dup a (- ($argcount func) ($len defargs))))
   (fun (bloc) (func ...defargs bloc))
   ($undef bloc) })
 
-(macro __count_placeholders (acc x ...xs) ($if (empty? xs)
+(macro __count_placeholders (acc x ...xs) ($if ($empty? xs)
     ($if (= "_" ($repr x))
       (+ 1 acc)
       acc)
@@ -61,14 +61,14 @@
       (__count_placeholders acc ...xs))))
 
 (macro __replace_placeholders (replacements x ...xs) {
-  ($if (empty? xs)
+  ($if ($empty? xs)
     ($if (= "_" ($repr x))
-      (head replacements)
+      ($head replacements)
       x)
     ($if (= "_" ($repr x))
       {
-        (head replacements)
-        (__replace_placeholders (tail replacements) ...xs) }
+        ($head replacements)
+        (__replace_placeholders ($tail replacements) ...xs) }
       {
         x
         (__replace_placeholders replacements ...xs) })) })
diff --git a/Math.ark b/Math.ark
index 8347356..8e7756a 100644
--- a/Math.ark
+++ b/Math.ark
@@ -255,7 +255,7 @@
 (let prime? (fun (n)
   (if (= 2 n)
     true
-    (if (or (= 0 (mod n 2)) (= 1 n))
+    (if (or (= 0 (mod n 2)) (= 1 n) (!= 0 (mod n 1)))
       false
       {
         (let k (ceil (+ 1 (sqrt n))))
@@ -276,6 +276,7 @@
 # @author https://github.com/Wafelack
 (let divs (fun (n) {
   (assert (>= n 1) "divs: n must be greater or equal to 1")
+  (assert (= 0 (mod n 1)) "divs: n must be an integer")
   (mut i 1)
   (mut divisors [])
   (let top (ceil (/ n 2)))
diff --git a/Prelude.ark b/Prelude.ark
new file mode 100644
index 0000000..fdd85bc
--- /dev/null
+++ b/Prelude.ark
@@ -0,0 +1,10 @@
+(import std.Dict)
+(import std.IO)
+(import std.List)
+(import std.Macros)
+(import std.Math)
+(import std.Random)
+(import std.Range)
+(import std.String)
+(import std.Switch)
+(import std.Sys)
diff --git a/String.ark b/String.ark
index e852193..5917cad 100644
--- a/String.ark
+++ b/String.ark
@@ -245,7 +245,7 @@
 # @param _string the string to get a slice of
 # @param _startingIndex the index in the string where to start slicing
 # @param _length the length of the slice
-# @details The original string is left unmodified. Example:
+# @details The original string is left unmodified.
 # =begin
 # (let message "hello world, I like goats")
 # (let slice (string:slice message 6 4))  # => worl
@@ -513,3 +513,53 @@
   (if (endsWith? _str _suffix)
     (slice _str 0 (- (len _str) (len _suffix)))
     _str)))
+
+# @brief Compute the levenshtein distance between two strings
+# @param _str1 string
+# @param _str2 string
+# =begin
+# (print (string:levenshteinDistance "arkscript" "arkscript"))  # 0
+# (print (string:levenshteinDistance "arkscript" "Orkscript"))  # 1
+# (print (string:levenshteinDistance "arkscript" "0rCscript"))  # 2
+# (print (string:levenshteinDistance "arkscript" "OrC"))  # 8
+# =end
+# @author https://github.com/SuperFola
+(let levenshteinDistance (fun (_str1 _str2) {
+  (let _len1 (+ (len _str1) 1))
+  (let _len2 (+ (len _str2) 1))
+  (mut _edit_distances (builtin__list:fill _len1 (builtin__list:fill _len2 0)))
+
+  (mut _i 0)
+  (while (< _i _len1) {
+    (@@= _edit_distances _i 0 _i)
+    (set _i (+ 1 _i)) })
+  (set _i 0)
+  (while (< _i _len2) {
+    (@@= _edit_distances 0 _i _i)
+    (set _i (+ 1 _i)) })
+
+  (set _i 1)
+  (while (< _i _len1) {
+    (mut _j 1)
+    (while (< _j _len2) {
+      (let _dist [
+        (+ 1 (@@ _edit_distances (- _i 1) _j))
+        (+ 1 (@@ _edit_distances _i (- _j 1)))
+        (+
+          (if (= (@ _str1 (- _i 1)) (@ _str2 (- _j 1)))
+            0
+            1)
+          (@@ _edit_distances (- _i 1) (- _j 1)))])
+      (@@=
+        _edit_distances
+        _i
+        _j
+        (if (and (< (@ _dist 0) (@ _dist 1)) (< (@ _dist 0) (@ _dist 2)))
+          (@ _dist 0)
+          (if (and (< (@ _dist 1) (@ _dist 0)) (< (@ _dist 1) (@ _dist 2)))
+            (@ _dist 1)
+            (@ _dist 2))))
+      (set _j (+ 1 _j)) })
+    (set _i (+ 1 _i)) })
+
+  (@@ _edit_distances (- _len1 1) (- _len2 1)) }))
diff --git a/Switch.ark b/Switch.ark
index 4417e97..550e8e8 100644
--- a/Switch.ark
+++ b/Switch.ark
@@ -18,4 +18,4 @@
     then
     (if (= value case)
       then
-      ($if (>= (len cases) 2) (switch value ...cases)))) })
+      ($if (>= ($len cases) 2) (switch value ...cases)))) })
diff --git a/tests/dict-tests.ark b/tests/dict-tests.ark
index 33dd3bd..06a5581 100644
--- a/tests/dict-tests.ark
+++ b/tests/dict-tests.ark
@@ -25,9 +25,8 @@
   (let filter_odd (fun (k v) (= 1 (mod v 2))))
 
   (test:case "comparison" {
-    # FIXME: the macro processor is using the macro version of `empty?`, even though we have an `$as-is` inside expect
-    (test:expect ($as-is (empty? (dict))))
-    (test:expect ($as-is (not (empty? (dict "a" 2)))))
+    (test:expect (empty? (dict)))
+    (test:expect (not (empty? (dict "a" 2))))
     (test:expect (not empty))
     (test:expect (not (not d)))
     (test:eq empty (dict))
@@ -68,8 +67,7 @@
     (test:eq (dict:size d) 6)
     (test:eq (dict:size d) (len d))
     (test:eq (dict:size (dict)) 0)
-    # FIXME: the macro processor is using the macro version of `len`, even though we have an `$as-is` inside eq
-    (test:eq (dict:size (dict)) ($as-is (len (dict))))
+    (test:eq (dict:size (dict)) (len (dict)))
     (test:eq (dict:size d3) 1)
     (test:eq (dict:size d3) (len d3))
     (test:eq (dict:size d4) 1) })
diff --git a/tests/macros-tests.ark b/tests/macros-tests.ark
index 2d940ba..864ae61 100644
--- a/tests/macros-tests.ark
+++ b/tests/macros-tests.ark
@@ -14,6 +14,7 @@
 (let test_func1 (partial test_func 1))
 (let test_func2 (partial test_func1 2))
 (let test_func3 (partial2 test_func 1 _ 3))
+(let test_func4 (partial2 test_func _ 2 _))
 
 (test:suite macros {
   (test:case "->" {
@@ -25,7 +26,9 @@
     (test:eq (test_func1 2 3) 6)
     (test:eq ($argcount test_func1) 2)
     (test:eq ($argcount test_func2) 1)
-    (test:eq (test_func3 2) 6) })
+    (test:eq ($argcount test_func4) 2)
+    (test:eq (test_func3 2) 6)
+    (test:eq (test_func4 1 3) 6) })
 
   (test:case "unless" {
     (unless false
diff --git a/tests/string-tests.ark b/tests/string-tests.ark
index 7968697..2737082 100644
--- a/tests/string-tests.ark
+++ b/tests/string-tests.ark
@@ -162,4 +162,10 @@
 
     (test:eq (string:removeSuffix "TestCase" "Case") "Test")
     (test:eq (string:removeSuffix "BaseTestCase" "Test") "BaseTestCase") })
+
+  (test:case "levenshteinDistance" {
+    (test:eq (string:levenshteinDistance "arkscript" "arkscript") 0)
+    (test:eq (string:levenshteinDistance "arkscript" "Orkscript") 1)
+    (test:eq (string:levenshteinDistance "arkscript" "0rCscript") 2)
+    (test:eq (string:levenshteinDistance "arkscript" "OrC") 8) })
 })