Container types are the most obvious. Lists, Arrays, Dictionaries, Vectors, Stacks. You'd be hard pressed to find code that doesn't use a container type of some kind.
Incidentally the problem is much smaller than in a statically typed language with containers.
Compare the difference between a Java list prior to generics and afterwards. Using it in Java was an orgy of object casts. This is not the case for dynamically typed languages.
In fact, the common approaches to containers valid in a statically typed language is largely wrong in a dynamic language.
Compare the difference between a Java list prior to generics and afterwards. Using it in Java was an orgy of object casts. This is not the case for dynamically typed languages.
In fact, the common approaches to containers valid in a statically typed language is largely wrong in a dynamic language.