[currymj]

maybe not a hello world, but even very rudimentary 20 LoC contracts for, say, keeping account balances can have reentrancy vulnerabilities when written in the obvious way. so your customer could just give themselves an infinite balance.

i don't think it's impossible to write secure smart contracts but it takes quite a bit of care even for simple stuff.

there are many issues that arise because your functions might be called by an adversary who has set up the stack in an evil way.

[edjere]

Agree with this, especially with the "it takes quite a bit of care even for simple stuff", but this should not discourage developers to do so. One of the reasons to build this kind of infrastructure is to set proper standards for smart contracts development which are currently missing. As long as we are aware that we need to be careful, and we raise the quality of the code and keep on developing tools to improve development as a whole things should keep on moving forward.