Why dynamic languages suck

I had a little bit of JScript that wasn't working as expected. I stared and stared at it... For a very long time... Here it is.

var splitDetails = details.split("\t");
for (var i=0; i<splitDetails.Length; i++)
{
  // do something
} 

The problem was that the //do something was never getting hit. Life would have been easier with a debugger but this was server-side JScript in Metastorm which doesn't support debugging so I was forced to just stare at it to work out what was wrong.

No doubt you're now shouting at your computer "you're a fecking idiot! The problem is obvious!" and perhaps you'd be right. Perhaps I was just having a senior moment, which I think I'm entitled to have at my age. For those of you who haven't spotted the error I'd typed length with an upper-case L.

So what happens here? JScript doesn't throw an error because I've tried to access a property that doesn't exist, instead it returns null. Then I presume it converts that to 0 for the loop test so never drops into the code inside the loop.

This kind of thing is all too easy in a dynamic language. If I was using a compiled statically-typed language the compiler would have picked up the problem immediately. Perhaps the advantages of dynamic languages outweigh these kind of problems but personally I'd rather have the crutch of a compiler.