There is type-instability only at global scope, that's the point. So when
you are using the repl (or just using the global scope) you won't have to
write types. My suggestion is only to disallow type-instability at inner
scopes so they become fully statically typed; the next step would be to
statically check functions before compilation, a real static check just
like you would get in say Java or or Haskell.
The advantages are way more than just linting. You would catch whole
categories of problems at copile time, before your code actually runs.
Imagine finding a problem after your code runs for hrs, or a web server
crash in production due to some untested code.... these things happen. This
would allow way better tooling: the tooling that statically typed languages
have (think Java, C#) is wayyyy better than that of dynamically typed
languages. And I say this even after considering PyCharm. The tools for
statically typed languages allow for safe refactorings, find usages,
definitions, automated documentation which is really sync'd with the code
and much more.
above I was just trying to demonstrate how some problems that currently use
dynamic typing could easily be converted to be type stable, and hence
statically typed. Yes, with the solution that I demonstrated above, when
using a file name known only at runtime inside a function, you would have
to write down the expected types, which doesn't seem like too much effort:
myvec = load_vector_from_hdf5_file(filename, vecname, Float64)
But now you get the advantage that the following code would fail at compile
time:
for i, v in enumerate(myvec)
println("element number "*string(i)*" is "*myvec[i])
end
Of course if you're using the repl you could just use the macro, or if you
want to do more automation at global scope just write a macro instead of a
function.
Seems to me that the advantages of type stable inner scopes easily
outweighs the inconvenience of having to write a few rare types. Julia can
be really be the 1st interactive language with statically typed guarantees
and tooling. BTW With good enough tooling the IDE could suggest the HDF5
vector type so in the long run this would represent really little cognitive
effort from the programmer.
