> You won't get what true "liveness" is until you work in Lisp or Smalltalk. The ability to change a function in a running program, without restarting it
This can be done in a number of other common languages today such as Java (JVM languages) and C# (probably all .NET languages). Most IDEs I've seen for those platforms support it.
Substantial enough changes to the code can require an application restart, but most changes you might make like changing the implementation of a function, adding new functions to a class, etc., will not. Hot Code Replacement (HCR) has been supported since Java 1.4: https://wiki.eclipse.org/FAQ_What_is_hot_code_replace%3F
Fully dynamic languages like Lisp and Smalltalk permit a greater degree of this than statically typed languages do, however, since they don't have types and a type system to wrangle with. When I've used it, hot code replacement supported most of the changes that conceptually make sense to support.
You'd be surprised to find out that Common Lisp has actually quite a strong type system (not Haskell-level but much better than C++/Java); just that it's optional. You get the best of both worlds — fast prototyping, and then when you decide upon the types, you can add type declarations, which usually result in (much!) faster code and robustness.
This can be done in a number of other common languages today such as Java (JVM languages) and C# (probably all .NET languages). Most IDEs I've seen for those platforms support it.
Substantial enough changes to the code can require an application restart, but most changes you might make like changing the implementation of a function, adding new functions to a class, etc., will not. Hot Code Replacement (HCR) has been supported since Java 1.4: https://wiki.eclipse.org/FAQ_What_is_hot_code_replace%3F
Fully dynamic languages like Lisp and Smalltalk permit a greater degree of this than statically typed languages do, however, since they don't have types and a type system to wrangle with. When I've used it, hot code replacement supported most of the changes that conceptually make sense to support.