Expose clojure.core/pr-on

Author: borkdude

src/sci/impl/io.cljc

@@ -82,6 +82,20 @@
             (print-method x w))
           nil))
 
+#?(:clj (defn core-pr-on
+          "Prints x to w under the interpreter's print settings. Exposed as the
+  private clojure.core/pr-on, which host code reaches through the var. The
+  host's own pr-on binds nothing, because there these settings are already
+  the ones in effect."
+          [x w]
+          (binding [*print-length* @print-length
+                    *print-level* @print-level
+                    *print-meta* @print-meta
+                    *print-namespace-maps* @print-namespace-maps
+                    *print-readably* @print-readably
+                    *print-dup* @print-dup-var]
+            (pr-on x w))))
+
 #?(:cljd (defn pr
            [& objs]
            (binding [*out* @out

src/sci/impl/namespaces.cljc

@@ -1366,6 +1366,7 @@
      'newline (copy-var sci.impl.io/newline clojure-core-ns {:name 'newline})
      'flush (copy-core-var sci.impl.io/flush)
      'pr (copy-var sci.impl.io/pr clojure-core-ns {:name 'pr})
+     #?@(:clj ['pr-on (new-var 'pr-on sci.impl.io/core-pr-on clojure-core-ns {:private true})])
      'prn (copy-core-var sci.impl.io/prn)
      'print (copy-core-var sci.impl.io/print)
      'println (copy-core-var sci.impl.io/println)

test/sci/io_test.cljc

@@ -2,7 +2,7 @@
   (:require
    [clojure.edn :as edn]
    [clojure.string :as str]
-   [clojure.test :as test :refer [deftest is]]
+   [clojure.test :as test :refer [deftest is testing]]
    [sci.core :as sci]
    [sci.test-utils :as tu]))
 
@@ -37,6 +37,20 @@
     (is (= "\"hello\"" (sci/with-out-str (eval* "(pr \"hello\")"))))
     (is (= "\n" (sci/with-out-str (eval* "(newline)"))))))
 
+#?(:cljd nil
+   :clj
+   (deftest pr-on-test
+     (when-not tu/native?
+       (testing "clojure.core/pr-on prints to the writer it is given"
+         (let [w (java.io.StringWriter.)]
+           (tu/eval* "(@#'clojure.core/pr-on (range 5) w)" {:namespaces {'user {'w w}}})
+           (is (= "(0 1 2 3 4)" (str w)))))
+       (testing "and under the interpreter's print settings"
+         (let [w (java.io.StringWriter.)]
+           (tu/eval* "(binding [*print-length* 3] (@#'clojure.core/pr-on (range 10) w))"
+                     {:namespaces {'user {'w w}}})
+           (is (= "(0 1 2 ...)" (str w))))))))
+
 (deftest print-length-test
   (when-not tu/native?
     (is (str/includes?