Practical reasons: The language is great for enhancing your style but in practice it's been one of the hardest languages I've come across to make do real things

Practical reasons: The language is great for enhancing your style but in practice it's been one of the hardest languages I've come across to make do real things. It interacts with the outside environment very poorly and more awkwardly. It's got multiple slightly incompatible implementations and it's library set is relatively light, green, wastefully overlapping and not very well maintained. There's a reason Java won't go away and that's that it runs everywhere releatively easily and interfaces with stuff acceptably well. Python is now doing a good job of this too. Lisp has a looong way to go on this front and I do speak from some limited experience. It's very pleasant if all you're doing is staying inside lisp and interacting only with your own code but as soon as it's asked to play nice with others it gets a lot less fun. And staying inwardly focused, never looking out and never talking to anyone else ultimately means get very little real productive work done. :(