[ANSI C Grammar](http://www.lysator.liu.se/c/ANSI-C-grammar-y.html)

[Awk Grammar](https://pubs.opengroup.org/onlinepubs/7908799/xcu/awk.html#tag_000_000_108_016)

[Original Awk Grammar](https://github.com/onetrueawk/awk/blob/master/awkgram.y)

[GAWK Grammar](http://git.savannah.gnu.org/cgit/gawk.git/tree/awkgram.y)

[Smalltalk-80: The Language and Its Implementation](http://web.archive.org/web/20070927190722/http://users.ipa.net/~dwighth/smalltalk/bluebook/bluebook_imp_toc.html) 
Adele Goldberg and David Robson

[The Java Virtual Machine Specification](https://docs.oracle.com/javase/specs/jvms/se7/html/index.html) Lindholm Yellin Bracha Buckley


[Perl operators](https://perldoc.perl.org/perlop#Regexp-Quote-Like-Operators)


["Generating LR syntax error messages from examples", Jeffery, ACM TOPLAS Volume 24 Issue 5 Sep 2003.](https://dl.acm.org/doi/abs/10.1145/937563.937566)



[Hindley Milner in Scala](http://dysphoria.net/2009/06/28/hindley-milner-type-inference-in-scala/)

[The Hindley-Milner Algorithm](http://web.archive.org/web/20050911123640/http://www.cs.berkeley.edu/~nikitab/courses/cs263/hm.html) in perl 
by Nikita Borisov


https://medium.com/@dhruvrajvanshi/type-inference-for-beginners-part-2-f39c33ca9513

