Implement in-ns as a function. (#824)

Co-authored-by: Benjamin Cherry <[email protected]>

src/sci/impl/analyzer.cljc

@@ -1355,14 +1355,6 @@
   (let [snd (second expr)]
     (->constant snd)))
 
-(defn analyze-in-ns [ctx expr]
-  (let [ns-expr (analyze ctx (second expr))]
-    (sci.impl.types/->Node
-     (let [ns-sym (types/eval ns-expr ctx bindings)]
-       (set-namespace! ctx ns-sym nil)
-       nil)
-     nil)))
-
 (defn analyze-import [_ctx expr]
   (let [args (rest expr)
         stack (assoc (meta expr)
@@ -1466,8 +1458,7 @@
                           import (analyze-import ctx expr)
                           or (return-or ctx expr (rest expr))
                           and (return-and ctx expr (rest expr))
-                          recur (return-recur ctx expr (analyze-children (without-recur-target ctx) (rest expr)))
-                          in-ns (analyze-in-ns ctx expr))
+                          recur (return-recur ctx expr (analyze-children (without-recur-target ctx) (rest expr))))
                         :else
                         (try
                           (if (macro? f)

src/sci/impl/namespaces.cljc

@@ -507,6 +507,12 @@
   (assert (symbol? ns-sym))
   (sci.impl.utils/namespace-object (:env ctx) ns-sym false nil))
 
+(defn sci-in-ns [ctx ns-sym]
+  (assert (symbol? ns-sym))
+  (when-not (sci-find-ns ctx ns-sym)
+    (sci-create-ns ctx ns-sym))
+  (sci.impl.utils/set-namespace! ctx ns-sym {}))
+
 (defn sci-the-ns [ctx x]
   (if (instance? #?(:clj sci.lang.Namespace
                     :cljs sci.lang/Namespace) x) x
@@ -1225,6 +1231,7 @@
    'ex-cause (copy-core-var ex-cause)
    'find-ns (core-var 'find-ns sci-find-ns true #_{:sci.impl/op needs-ctx})
    'create-ns (core-var 'create-ns sci-create-ns true #_{:sci.impl/op needs-ctx})
+   'in-ns (core-var 'in-ns sci-in-ns true #_{:sci.impl/op needs-ctx})
    'find-var (core-var 'find-var sci-find-var true)
    'first (copy-core-var first)
    'float? (copy-core-var float?)

test/sci/namespaces_test.cljc

@@ -107,6 +107,11 @@
   (is (= :clojure.string/foo (eval* "(in-ns 'foo) (require '[clojure.string :as str]) ::str/foo")))
   (is (= :clojure.string/foo (eval* "(ns foo (:require [clojure.string :as s])) ::s/foo"))))
 
+(deftest in-ns-test
+  (is (= :user/foo (eval* "::foo")))
+  (is (= :bar/foo (eval* "(in-ns 'bar) ::foo")))
+  (is (= :bar/foo (eval* "(in-ns 'bar) (def just-one-ns ::foo) (in-ns 'bar) just-one-ns"))))
+
 (deftest vars-partitioned-by-namespace-test
   (is (= 10 (eval* "(in-ns 'foo) (def x 10) (in-ns 'bar) (def x 11) (in-ns 'foo) x"))))