[Haskell-cafe] Is the #functional programming paradigm antithetical to efficient strings? #Haskell

[Alex Belanger]

That's not just about Haskell, it's C.S. in general.

You're always going to make space and time tradeoffs.

Funny how the same constraints appear in physics; I wonder if it is trying
to tell us something...

- nitrix
On Jul 11, 2016 8:54 AM, "David Fox" <dsf at seereason.com> wrote:

On Sun, Jul 10, 2016 at 11:44 AM, KC <kc1956 at gmail.com> wrote:

> Is the #functional programming paradigm antithetical to efficient strings?
> #Haskell
>
 ​I can certainly see how it might seem so.  Our main string
representation​ uses about 10 times more memory than seems necessary, and
is relatively fast, though probably not compared to C.  Recently I spent
some time looking into how to reduce this memory overhead, and I modified
the pretty library (https://github.com/ddssff/pretty/tree/textdetails) so
it could use any type that was an instance of ListLike and StringLike (
https://github.com/JohnLato/listlike).  Then I tried the UnitLargeDoc test
with several different data types.  This just concatenates a list of ten
million "Hello" strings.  Using String this happens in about 5 seconds.
Using strict or lazy Text it immediately blew the stack.  When I increased
the stack size to over 1GB it took minutes to complete.  When I used the
Data.Text.Lazy.Builder type instead it took about 30 seconds to complete.
Results with utf8 encoded ByteStrings were siimilar.

When I mentioned some of this, I was told "different data structures for
different purposes", which sort of makes sense, but honestly if Haskell is
a language where you have to sit down and choose a representation every
time you want to build some text, I get a bit discouraged.

So is functional programming antithetical to efficient strings?  In theory
maybe not, but I would love to see some hard evidence.

</rant>

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