Merge pull request #4005 from nbuwe/topic-clu

Add topic "clu"

topics/clu/index.md

@@ -0,0 +1,10 @@
+---
+created_by: Barbara Liskov et al.
+display_name: CLU
+released: 1975
+short_description: CLU was the first implemented programming language to provide direct linguistic support for data abstraction.
+topic: clu
+url: https://pmg.csail.mit.edu/CLU.html
+wikipedia_url: https://en.wikipedia.org/wiki/CLU_(programming_language)
+---
+CLU was the first implemented programming language to provide direct linguistic support for data abstraction.  CLU contains a number of other interesting and influential features, including checked exceptions, iterators, and parametric polymorphism.