When I have started my carrier, it was unimaginable to use a dynamic language in a serious project. I was taught(!?) that the difference of development cost was

When I have started my carrier, it was unimaginable to use a dynamic language in a serious project. I was taught(!?) that the difference of development cost was very small. The mentalities have evolved. People know that you can drastically reduce the development costs (of small projects) by using dynamic languages. We know also that maintenance is more costly. Static languages are always improving to support features that used to exist only in dynamic languages. Dynamic languages evolve to support optional typing. The differences are reducing, but I think there is still a need for the 2 kind of languages. Often they are combined in big projects. For example c++/javascript in browser or c++/guile.