From 946378510f1dd542cc2f30efe22a16da69749840 Mon Sep 17 00:00:00 2001
From: Andrey Orst <andreyorst@gmail.com>
Date: Thu, 29 Oct 2020 19:55:31 +0300
Subject: feature: functions to access table values

---
 core.fnl      | 20 ++++++++++++++++++++
 core_test.fnl | 20 +++++++++++++++++++-
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/core.fnl b/core.fnl
index b993863..d151c77 100644
--- a/core.fnl
+++ b/core.fnl
@@ -397,4 +397,24 @@ oppisite truth value."
      (set (i k) (next kvs i)))
    tbl))
 
+(fn& core.get
+  "Get value from the table by accessing it with a `key'.
+Accepts additional `not-found' as a marker to return if value wasn't
+found in the table."
+  ([tbl key] (get tbl key nil))
+  ([tbl key not-found]
+   (if-some [res (. tbl key)]
+     res
+     not-found)))
+
+(fn& core.get-in
+  "Get value from nested set of tables by providing key sequence.
+Accepts additional `not-found' as a marker to return if value wasn't
+found in the table."
+  ([tbl keys] (get-in tbl keys nil))
+  ([tbl keys not-found]
+   (if-some [res (. tbl (. keys 1))]
+     (get-in tbl [(unpack tbl 2)] not-found)
+     not-found)))
+
 core
diff --git a/core_test.fnl b/core_test.fnl
index 9b0359c..d607935 100644
--- a/core_test.fnl
+++ b/core_test.fnl
@@ -46,7 +46,9 @@
   : reverse
   : inc
   : dec
-  : assoc}
+  : assoc
+  : get
+  : get-in}
  (require :core))
 
 (deftest equality
@@ -425,3 +427,19 @@
   (testing dec
     (assert-eq (dec 1) 0)
     (assert-eq (dec -1) -2)))
+
+(deftest table-access
+  (testing get
+    (assert-eq (get {:key1 10 :key2 20} :key1) 10)
+    (assert-eq (get {:key1 10 :key2 20} :key1 false) 10)
+    (assert-eq (get {:key1 10 :key2 20} :key3 false) false)
+    (assert-eq (get {:key1 10 :key2 20} :key3) nil))
+
+  (testing get
+    (local t {:a {:b {:c 10}}})
+    (assert-eq (get t [:a]) {:b {:c 10}})
+    (assert-eq (get t [:a :b]) {:c 10})
+    (assert-eq (get t [:a :b :c]) 10)
+    (assert-eq (get t [:a :b :c] false) 10)
+    (assert-eq (get t [:a :b :d] false) false)
+    (assert-eq (get t [:a :b :d]) nil)))
-- 
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