feat: make empty? an interface (#1139)

core/Array.carp

@@ -46,6 +46,7 @@ It will sum the previous sum with each new value, starting at `0`.")
   (doc empty? "checks whether the array `a` is empty.")
   (defn empty? [a]
     (= (Array.length a) 0))
+  (implements empty? Array.empty?)
 
   (doc any? "checks whether any of the elements in `a` match the function `f`.")
   (defn any? [f a]

core/Interfaces.carp

@@ -67,3 +67,5 @@
 (definterface slice (Fn [&a Int Int] a))
 
 (definterface blit (Fn [a] a)) ; For types that can be freely memcopied -- exact name is up for discussion
+
+(definterface empty? (Fn [&a] Bool))

core/Map.carp

@@ -288,7 +288,8 @@
 
   (doc empty? "Check whether the map m is empty.")
   (defn empty? [m]
-    (= @(len m) 0))
+    (= (Map.length m) 0))
+  (implements empty? Map.empty?)
 
   (doc remove "Remove the value under the key k from the map m.")
   (defn remove [m k]
@@ -520,7 +521,8 @@
 
   (doc empty? "Check whether the set s is empty.")
   (defn empty? [s]
-    (= (length s) 0))
+    (= (Set.length s) 0))
+  (implements empty? Set.empty?)
 
   (doc remove "Remove the value `v` from the set `s`.")
   (defn remove [s v]

core/StaticArray.carp

@@ -52,6 +52,7 @@
   (doc empty? "checks whether the array `a` is empty.")
   (defn empty? [a]
     (= (StaticArray.length a) 0))
+  (implements empty? StaticArray.empty?)
 
   (doc any? "checks whether any of the elements in `a` match the function `f`.")
   (defn any? [f a]

core/String.carp

@@ -73,6 +73,7 @@
   (doc empty? "Check if the string is the empty string.")
   (defn empty? [s]
     (Int.= (length s) 0))
+  (implements empty? String.empty?)
 
   (doc slice "Return part of a string, beginning at index `a` and ending at index `b`.")
   (defn slice [s a b]

test/string.carp

@@ -72,7 +72,7 @@
                (empty? "")
                "empty? returns true on empty string")
   (assert-true test
-               (empty? &(zero))
+               (empty? &(the String (zero)))
                "empty? returns true on (zero)")
   (assert-equal test
                 &[\e \r \i \k]