Re: Haskell, anyone?

[Mark Carroll <mtbc@bcs.org>]

On 15 Nov 2015, mockturtle wrote:

> I recently read in the Italian version of Linux Format an interview to Katie
> Miller. It got me intrigued the fact that when she talks about Haskell, she
> says things that usually Ada enthusiasts say about Ada ("when it compiles, it
> runs...", "the number of bugs is reduced...").

Katie is correct. Among other things, especially with the help of some
of the extensions, Haskell offers a strong static type system that is
very expressive and the compiler is good at checking those claims.
Getting my Haskell code to compile at all is most of the debugging work.
It is nice, for instance, to be able to declare things as numerical that
compile to simply being a basic number but in the source are different
types that the compiler's analysis won't let me mix up accidentally --
i.e. the type information can sometimes be used then discarded -- or to
be able to declare that two types have some relationship such that, in
the right context, if I know what one of the types is, I can then be
sure what the other is.

> I remembered that some time ago
> I met someone that was enthusiast both about Ada and Haskell (when I said that
> I program in Ada, he said something "Finally! Now I need to find someone who
> likes Haskell."
>
> The question should be obvious: it seems that Haskell and Ada would attract
> the same kind of person; does someone here know and like Haskell as well?

"As well" is strong, as I don't use Ada. (-: Partly because of Haskell's
run-time system and lazy-by-default evaluation, while it /can/ be fast
in the hands of skilled practitioner, and the modern compilers can do
impressive optimization (like stream fusion), and Haskell does offer
powerful concurrency such as software transactional memory, it would be
a challenge to use it for real-time systems for which one wants to be
sure of performance: I wouldn't want to be using it for programming an
anti-ballistic missile. Basically, Haskell /is/ really great for safety
and correctness but, unless fans of Haskell can correct me, I'd expect
that Ada has the edge when time and space really matter. Languages like
Idris might shine the light toward a way forward, but right now they're
research projects, not for production code.

-- Mark