feat: make reseeding of Random at startup configurable (#1161)

* fix: respect quotes in macro expand

* feat: make reseeding of Random at startup configurable

* refactor: better reseed api

core/Random.carp

@@ -27,12 +27,28 @@
       (set! s (mod (+ (* s a) c) m))
       (/ s m)))
 
-  (private _)
   (hidden _)
   (doc _ "forces reseeding based on the current time at program start")
-  (def _ (do (seed) 0))
+  (def _ (do (seed) true))
+
+  (doc gen-seed-at-startup "toggles reseeding the random number generator at startup.")
+  (defmacro gen-seed-at-startup [toggle]
+    (if toggle
+      (eval '(defmodule Random (def _ (do (seed) true))))
+      (eval '(defmodule Random (def _ (do false))))))
+
+   (doc gen-seed-at-startup? "checks whether the random number generator was reseeded at startup.
+
+Use `Dynamic.Random.gen-seed-at-startup?` to check this in dynamic code.")
+  (defn gen-seed-at-startup? [] _)
 )
 
+(defmodule Dynamic
+  (defmodule Random
+    (doc gen-seed-at-startup? "checks whether the random number generator will be reseeded at startup.")
+    (defmacro gen-seed-at-startup? []
+      (last (last (s-expr Random._))))))
+
 (defmodule Int
   (defn random-between [lower upper]
     (let [diff (- upper lower)]

test/random-seed.carp

@@ -0,0 +1,35 @@
+(load "Test.carp")
+
+(use-all Random Test)
+
+(def reseed-before? (Dynamic.Random.gen-seed-at-startup?))
+
+(Random.gen-seed-at-startup false)
+
+(def reseed-after? (Dynamic.Random.gen-seed-at-startup?))
+
+(Random.gen-seed-at-startup true)
+
+(def reseed-redo? (Dynamic.Random.gen-seed-at-startup?))
+
+(Random.gen-seed-at-startup false)
+
+(deftest test
+  (assert-true test
+               reseed-before?
+               "reseeding is on by default")
+  (assert-false test
+                reseed-after?
+                "reseeding can be disabled")
+  (assert-true test
+                reseed-redo?
+                "reseeding can be re-enabled")
+  (assert-op test
+             0.658908 ; will always be the initial if not reseeded
+             (Random.random)
+             "deterministic randomization works as expected"
+             Double.approx)
+  (assert-false test
+                (Random.gen-seed-at-startup?)
+                "reseed can be checked statically as well")
+)