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Comment by ekr | Hacker News Reader

Never underestimate the edit-compile-test loop. It has an huge impact on productivity.

Well with stronger type guarantees, a lot of the "test" part of that loop gets pushed into "compile".

Indeed the core loop becomes edit-typecheck, and while the compiler can be slow, the type checker tends to be a lot faster than the test suite.

The biggest win for that is going to be incremental compilation. I can't wait for that to stabilize.

Can we have the best of both worlds?

AKA, REPL: Read Evaluate Print Loop.

No, a REPL is an interactive program, whereas the ECT loop belongs to the workflow of programming.

So how would you describe the experience of languages that offer both a REPL and also have integrated toolchains for AOT compilation to native code?

Nice. I would describe the experience (and the languages) as nice. And respectful of my time.*

* Waiting patiently for my JDK9 JShell

There used to be a program called BeanShell that tried to provide a REPL for Java, but it was not as nice as the REPLs offered by, e.g. Python or Ruby (Let alone Lisps where the debugger is integrated into the REPL). OTOH, I looked at it years ago, so maybe it has gotten better (or it stagnated completely).

OCaml offers a great REPL-experience in the form of `coretop`. It's got auto-complete that makes exploration awesome/easy. It feels very much like IPython.

OCaml installations tend to come with both a native compiler and a byte-code compiler/runtime, so you really get the best of both worlds there - minus some occasional hiccups in the build process.

OCaml was one of the languages I had in mind when I made the remark. :)

A REPL is just an ECT loop speed up enough to be actually good.

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