When comparing Python (via Skulpt) vs Idris, the Slant community recommends Idris for most people. In the question“What are the best languages that compile to JavaScript? ” Idris is ranked 23rd while Python (via Skulpt) is ranked 34th. The most important reason people chose Idris is:
Idris not only has support for type classes, but is a fully dependently typed language, giving you the full power to statically verify your code.
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Pros
Pro Suspensions
You can write blocking methods that don't cause the whole page to hang, something difficult to do in languages targeting Javascript.
Pro Interactive REPL
You can evaluate new Python code in the browser written by the user.
Pro Full dependent types
Idris not only has support for type classes, but is a fully dependently typed language, giving you the full power to statically verify your code.
Pro Domain driven design and type driven development
Because of full dependent types in Idris, the programmer can focus more on modelling the domain with types and waste less time fixing common bugs that the type checker will catch. Dependent types help apply type driven development and a lot of code auto generation, making the compiler and type checker an ally in developing working software instead of just getting in the way.
Cons
Con Python 2.6
Skulpt implements an outdated version of the Python language.
Con Not widely used
Con Not widely used
Con Weaker type inference
As type inference is undecidable for dependently-typed languages, Idris cannot offer the full type inference that Haskell supports, and so more type annotations will be needed.
Con Different semantics from Haskell
Idris, while similar to Haskell, has strict semantics, which may cause some confusion if your backend is done in Haskell. If using Idris, it would make sense to do the backend in Idris as well, if not for the fact that Idris currently has fewer libraries available for web development than Haskell.