When comparing Elixir vs Pony, the Slant community recommends Elixir for most people. In the question“What are the best (productivity-enhancing, well-designed, and concise, rather than just popular or time-tested) programming languages?” Elixir is ranked 3rd while Pony is ranked 22nd. The most important reason people chose Elixir is:
Leverages the existing Erlang BEAM VM
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Great for concurrency
Leverages the existing Erlang BEAM VM

Pro Great getting started tutorials
The tutorials are very clear and concise (even for a person not used to functional programming). Plus they are also very mobile friendly.
Pro Powerful metaprogramming
Write code that writes code with Elixir macros. Macros make metaprogramming possible and define the language itself.
Pro Full access to Erlang functions
You can call Erlang functions directly without any overhead: https://elixir-lang.org/getting-started/erlang-libraries.html
Pro Scalability
Elixir programming is ideal for applications that have many users or are actively growing their audience. Elixir can easily cope with much traffic without extra costs for additional servers.
More details can be found here.
Pro Great as a first functional programming language!

Pro Great documentation
Elixir's documentation is very good. It covers everything and always helps solving any problem you may have. It's also always available from the terminal.

Pro Syntax is similar to Ruby, making it familiar for people used to OOP
All of the benefits of Erlang; without as steep a learning curve of prolog based syntax. Elixir is heavily inspired by Ruby's syntax which many people love.

Pro Easy to download libraries
Comes with built in build tool called "mix". This will automatically download libraries and put them in the scope of the application when you add them to the "deps" function and run mix deps.get
Pro Concurrency model based on actors
The unique type system allows the compiler to automatically schedule actors on threads, giving you reliable concurrency for free.
Pro Reliable
Because of its capabilities secure type system, provided you don't use the C FFI, references will never be stale, race conditions are effectively impossible, deadlocks don't happen because locks and mutexes are never needed, and processes never crash because all exceptions must be handled. (Barring compiler bugs or external memory corruption, of course.) Pony programs can still lock up due to infinite loops, like any Turing-complete language.
Pro High performance
Compiles to native code, and features an intelligent garbage collector that takes advantage of the actor architecture to get essentially free garbage collection.
Pro Trivially simple C FFI
Calling low-level C functions is as simple as use "lib:clibrary"
and @c_function_name[return_type](parameter:type)
. Linking C to Pony libraries is just as easy, as the Pony compiler will generate appropriate header files.
Cons
Con Deployment is still not as easy as it should be
Con Some design choices may seem strange
Some design choices could have been a little more appealing, for example: using "do...end" comes natural in Ruby for blocks but Elixir uses them for everything and it looks pretty weird:
Enum.map [1, 2, 3], fn(x) -> x * 2 end
or
receive do
{:hello, msg} -> msg
{:world, msg} -> "won't match"
end
Con All exceptions must be caught
The compiler enforces this, so code is littered with try
s.
Con Limited documentation
As Pony is such a new language, documentation is relatively light, and tutorials are few and far-between.
Con Few libraries
Con Garbage collector can't run until you yield
A long-running behavior can leak memory because the garbage collector has no chance to run.
Con Limited tooling
There's no IDE. Debuggers are fairly basic. Pony is too young to have much of an ecosystem.
Con Divide by zero is allowed
And instead of some sensible result like NaN or Inf, the answer is zero! Most languages would just raise an exception (and Pony used to do this), but since the compiler enforces the rule that "all exceptions must be caught" the proliferation of try
s was determined to be too burdensome on the programmer. This makes the whole design of the exception system questionable.
Con Unstable API
Pony is not ready for production. It has yet to release version 1.0, and there are frequent breaking changes.
Con Difficult learning curve
The type system uses a capabilities-oriented approach to reference semantics, which can be difficult to wrap your head around at first. The lack of more common object-oriented features and the preference for simplicity over familiarity can make it difficult for new users to model their program design.
