Soft typing by Robert Cartwright and Mike Fagan

This paper from 1991 introduces an approach for runtime type checking and type
coercion. It is relevant because this approach is being considered for addition
into Ruby 3.0.

This paper will be discussed at PWL Berlin.

plt/README.md

@@ -5,3 +5,5 @@
 * [Programming and Reasoning with Algebraic Effects and Dependent Types](http://eb.host.cs.st-andrews.ac.uk/drafts/effects.pdf)
 
 * [Programming Languages: History and Future](http://www.csee.umbc.edu/courses/undergraduate/CMSC331/resources/papers/sammet1972.pdf)
+
+* [Soft Typing](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.24.9333&rep=rep1&type=pdf)