Crystal

[thedeemon]

On Sunday, 17 February 2013 at 06:28:09 UTC, Ary Borenszweig 
wrote:
> One time I asked in this newsgroup if it was possible to have 
> an "auto" keyword for function/method arguments. And... why not 
> make all functions/methods be templates on the type of its 
> arguments?
>
> I think nobody liked this idea. I said "Ruby is like this: you 
> never specify types in method definitions".
>
> I started thinking about this idea: a compiled language that 
> looked like a dynamic language. Is it possible?

I think everyone who wants to create languages should first 
familiarize himself with ML family of languages and especially 
OCaml. It's got global type inference done right, you can write 
big programs never specifying types of arguments of functions, 
they all got inferred, and not just to first occurrence but to 
most general (polymorphic) form. The compiler is incredibly fast 
and generated code is pretty fast too (approximately as fast as 
Java).

Things to learn: Damas-Hindley-Milner, structural typing, row 
polymorphism.

So your questions are already answered ages ago: yes, it is 
possible to have static typing with conciseness of dynamic 
languages, speed of static languages and a fast compiler which 
inferences types.

Also, knowing OCaml will make your life much easier as a compiler 
developer. Writing compilers is much much easier and more 
convenient in ML than in Ruby, I know it from first-hand 
experience, I did both in the past.