The CMUCL compiler and some of it descendants (especially SBCL) has been using type declarations and inference not only for optimizations. see for SBCL: http:

The CMUCL compiler and some of it descendants (especially SBCL) has been using type declarations and inference not only for optimizations. see for SBCL: http://www.sbcl.org/manual/index.html#Handling-of-Types http://www.sbcl.org/manual/index.html#Handling-of-Types