2 files changed, 24 insertions, 0 deletions
diff --git a/prolog/problems/lists/len_2/common.py b/prolog/problems/lists/len_2/common.py
new file mode 100644
index 0000000..62be9cc
--- /dev/null
+++ b/prolog/problems/lists/len_2/common.py
@@ -0,0 +1,12 @@
+id = 119
+group = 'lists'
+number = 26
+visible = True
+facts = None
+
+solution = '''\
+len([], 0).
+len([_|T], Len) :-
+  len(T, LenT),
+  Len is LenT + 1.
+'''
diff --git a/prolog/problems/lists/len_2/en.py b/prolog/problems/lists/len_2/en.py
new file mode 100644
index 0000000..b3e277c
--- /dev/null
+++ b/prolog/problems/lists/len_2/en.py
@@ -0,0 +1,12 @@
+id = 119
+name = 'len/2'
+slug = 'find the length of a list'
+
+description = '''\
+<p><code>len(L, Len)</code>: <code>Len</code> is the length of the list <code>L</code>.</p>
+<pre>
+  ?- len([1,2,3], Len).
+    Len = 3.
+</pre>'''
+
+hint = {}