Don't check the type of arguments to inc, odd?, etc.

This allows them to be used with numeric types that aren't built in, such as NumPy arrays. Because Python uses duck typing, there's generally no way to know in advance whether a given value will accept a given operator. Of course, things like `(inc "hello")` will still raise a `TypeError`, because so does `(+ "hello" 1)`.

hy/core/language.hy

@@ -39,10 +39,6 @@
 (import [hy.lex [LexException PrematureEndOfInput tokenize]])
 (import [hy.compiler [HyASTCompiler]])
 
-(defn _numeric-check [x]
-  (if (not (numeric? x))
-    (raise (TypeError (.format "{0!r} is not a number" x)))))
-
 (defn butlast [coll]
   "Returns coll except of last element."
   (drop-last 1 coll))
@@ -66,7 +62,6 @@
 
 (defn dec [n]
   "Decrement n by 1"
-  (_numeric-check n)
   (- n 1))
 
 (defn disassemble [tree &optional [codegen false]]
@@ -170,7 +165,6 @@
 
 (defn even? [n]
   "Return true if n is an even number"
-  (_numeric-check n)
   (= (% n 2) 0))
 
 (defn every? [pred coll]
@@ -239,7 +233,6 @@
 
 (defn inc [n]
   "Increment n by 1"
-  (_numeric-check n)
   (+ n 1))
 
 (defn instance? [klass x]
@@ -325,7 +318,6 @@
 
 (defn neg? [n]
   "Return true if n is < 0"
-  (_numeric-check n)
   (< n 0))
 
 (defn none? [x]
@@ -347,7 +339,6 @@
 
 (defn odd? [n]
   "Return true if n is an odd number"
-  (_numeric-check n)
   (= (% n 2) 1))
 
 (def -sentinel (object))
@@ -364,7 +355,6 @@
 
 (defn pos? [n]
   "Return true if n is > 0"
-  (_numeric_check n)
   (> n 0))
 
 (defn rest [coll]
@@ -415,7 +405,6 @@
 
 (defn zero? [n]
   "Return true if n is 0"
-  (_numeric_check n)
   (= n 0))
 
 (defn read [&optional [from-file sys.stdin]

tests/native_tests/core.hy

@@ -33,6 +33,11 @@
 (defn assert-nil [x]
   (assert (is x nil)))
 
+(defn assert-requires-num [f]
+  (for [x ["foo" [] None]]
+    (assert-true (try (do (f x) False)
+                 (except [e [TypeError]] True)))))
+
 (defn test-coll? []
   "NATIVE: testing coll?"
   (assert-true (coll? [1 2 3]))
@@ -66,12 +71,7 @@
   (assert-equal 0 (dec 1))
   (assert-equal -1 (dec 0))
   (assert-equal 0 (dec (dec 2)))
-  (try (do (dec "foo") (assert False))
+  (assert-requires-num dec))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (dec []) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (dec None) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-setv []
   "NATIVE: testing setv mutation"
@@ -173,12 +173,7 @@
   (assert-true (even? -2))
   (assert-false (even? 1))
   (assert-true (even? 0))
-  (try (even? "foo")
+  (assert-requires-num even?))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (even? [])
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (even? None)
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-every? []
   "NATIVE: testing the every? function"
@@ -263,12 +258,11 @@
   "NATIVE: testing the inc function"
   (assert-equal 3 (inc 2))
   (assert-equal 0 (inc -1))
-  (try (do (inc "foo") (assert False))
+  (assert-requires-num inc)
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
+
-  (try (do (inc []) (assert False))
+  (defclass X [object]
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
+    [__add__ (fn [self other] (.format "__add__ got {}" other))])
-  (try (do (inc None) (assert False))
+  (assert-equal (inc (X)) "__add__ got 1"))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-instance []
   "NATIVE: testing instance? function"
@@ -394,24 +388,13 @@
   (assert-true (neg? -2))
   (assert-false (neg? 1))
   (assert-false (neg? 0))
-  (try (do (neg? "foo") (assert False))
+  (assert-requires-num neg?))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (neg? []) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (neg? None) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-zero []
   "NATIVE: testing the zero? function"
   (assert-false (zero? -2))
   (assert-false (zero? 1))
-  (assert-true (zero? 0))
+  (assert-true (zero? 0)))
-  (try (do (zero? "foo") (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (zero? []) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (zero? None) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-none []
   "NATIVE: testing for `is None`"
@@ -463,12 +446,7 @@
   (assert-true (odd? -3))
   (assert-true (odd? 1))
   (assert-false (odd? 0))
-  (try (do (odd? "foo") (assert False))
+  (assert-requires-num odd?))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (odd? []) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (odd? None) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-partition []
   "NATIVE: testing the partition function"
@@ -500,12 +478,7 @@
   (assert-true (pos? 2))
   (assert-false (pos? -1))
   (assert-false (pos? 0))
-  (try (do (pos? "foo") (assert False))
+  (assert-requires-num pos?))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (pos? []) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e)))))
-  (try (do (pos? None) (assert False))
-       (except [e [TypeError]] (assert (in "not a number" (str e))))))
 
 (defn test-remove []
   "NATIVE: testing the remove function"