Analysis of programming languages on Rosetta

[Andrei Alexandrescu via Digitalmars-d]

On 9/24/14, 2:43 PM, Joakim wrote:
> On Wednesday, 24 September 2014 at 19:38:37 UTC, bearophile wrote:
>> Joakim:
>>
>>> I wonder why they found Haskell to be so slow, I thought it was
>>> compiled.
>>
>> The first reason for the performance of programs is how much care the
>> programmer has to write a fast program, secondly how good the chosen
>> algorithms are, and only then at a third place there are language
>> implementations.
>
> So Haskell programmers don't care about fast programs and don't know how
> to choose good algorithms? ;)

Sadly that's only half of a joke.

Google for "Haskell tutorial", you'll get 
http://www.haskell.org/haskellwiki/Tutorials at the top. First "best 
place to start" leads to 
http://www.seas.upenn.edu/~cis194/lectures/01-intro.html. On that page, 
literally the first function defined is:

sumtorial :: Integer -> Integer
sumtorial 0 = 0
sumtorial n = n + sumtorial (n-1)

i.e. an linear-space way of doing summation. Just a bit below there's:

-- Compute the length of a list of Integers.
intListLength :: [Integer] -> Integer
intListLength []     = 0
intListLength (x:xs) = 1 + intListLength xs

i.e. an linear-space way of computing length. These are functions that 
are computationally bankrupt, we're not talking small constant fish here.

Well maybe that's not a very good tutorial. Let's move on to the second 
recommended reading, the famous "Learn You a Haskell for Great Good!" 
Sure that's going to be awesome. The first nontrivial function the 
tutorial ever defines from first principles at 
http://learnyouahaskell.com/syntax-in-functions#pattern-matching is...

factorial :: (Integral a) => a -> a
factorial 0 = 1
factorial n = n * factorial (n - 1)

... again, a gratuitously linear-space function.

Someone should do hard time for this.


Andrei