Update README.md

Author: ericelliott

README.md

@@ -14,4 +14,14 @@ ESLint has deprecated some old rules. Bring the `.eslintrc` up to date with the
 
 ### [Runtime rtype parser](https://github.com/ericelliott/rtype/issues/62) #advanced
 
+Experience with compilers, type theory, language design would be helpful.
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 Write a function that takes an rtype interface description as a string and returns an object that can be used for runtime introspection and type checking.
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+Useful background:
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+* The [Stanford Compilers course](https://www.coursera.org/course/compilers) (free online lectures)
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+If you're curious about types, see the [introduction to types](https://class.coursera.org/compilers/lecture/45) from the Stanford Compiler course.
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+