Janin posted:

I'm not denying that it's *possible* to write unreadable code in Haskell. Rather, I'm simply stating that properly written Haskell is more readable than properly written Python.

Type signatures, types, and especially category theory have nothing to do with it. In fact, category theory is irrelevant to 99% of Haskell programmers.

NotShadowStar posted:

code:

  context "when reading an invalid string" do
    subject { "xxx" }
    its(:read_ber!) { should be nil }
    it { should eq "xxx "}
  end

If you don't understand that then...

Janin posted:

"DSL" is what Ruby people call libraries

Zombywuf posted:

Oh hey, I've got some mutable state, and at intermediary mutations of said state I need to print bits of it to stdout.

Derpes Simplex posted:

If this is true then my god this is the biggest horror in the thread

Access Violation posted:

Here's one I've never understood with PHP:

<?
for($i = "A"; $i < "Z"; $i++)
{
echo "$i ";
}
?>

output: A->Y

<?
for($i = "A"; $i <= "Z"; $i++)
{
echo "$i ";
}
?>

output: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z AA AB AC AD AE ... YZ

Yes, I know the correct way of doing this, but why does it behave this way?

A A 2 3 5 8 K posted:

The first block terminates when $i is 'Z' because 'Z' is not less than 'Z'. The second block doesn't terminate when $i is 'Z' because 'Z' <= 'Z'. Incrementing the string 'Z' in php apparently produces 'AA' because, why not? The sequence continues until 'ZZ' fails to evaluate <= 'Z'.

A A 2 3 5 8 K posted:

The first block terminates when $i is 'Z' because 'Z' is not less than 'Z'. The second block doesn't terminate when $i is 'Z' because 'Z' <= 'Z'. Incrementing the string 'Z' in php apparently produces 'AA' because, why not? The sequence continues until 'ZZ' fails to evaluate <= 'Z'.

And now that I've convinced you never to use PHP, you'll never have to worry about it again.

Janin posted:

Good thing Haskell makes working with mutable state easy, and can write to stdout! Boy, any language which can't do either of those must be really hard to use.

Zombywuf posted:

A language that makes it hard to do both at the same time should have been drowned at birth.

Janin posted:

Agreed! Boy, I sure am glad Haskell is not such a language.

Janin posted:

I don't really know what you're getting at, so yeah.

Are you implying that Haskell doesn't support mutable values? That's obviously false -- even ignoring pointers, the standard library has mutable types for various purposes (pointers, memory buffers, hash tables, mutex-protected storage, transactional storage).

Are you implying that Haskell doesn't support writing to stdout? I suppose there's a lot of weird propaganda about how academical it is, but come on, give us some credit.

If neither of these, then I'm lost about what you're trying to claim.

Janin posted:

I don't see what monads or combinators have to do with this. Combining mutable containers and output is trivial:

code:

import Data.HashTable as HashTable

main = do
        table <- HashTable.new (==) hashString
        insert table "go" 0
        toList table >>= print
        insert table "back" 1
        toList table >>= print
        insert table "to" 2
        toList table >>= print
        insert table "gbs" 3
        toList table >>= print

Janin posted:

Oh no, using IO to perform I/O? That's, like, too much IO!

I'd like to hear your suggestions on how to print to stdout without performing I/O.

Data.HashTable posted:

code:

new :: (key -> key -> Bool) -> (key -> Int32) -> IO (HashTable key val)

Janin posted:

Are you really complaining that a mutable data structure is marked as mutable? Really?

Zombywuf posted:

Yerrrs, the IO monad marks data as mutable. This is why MonadState derives from it.

Do you actually know Haskell?

ShoulderDaemon posted:

If you really want to use a monad transformer or something, it doesn't look much worse. It just performs a little weird because you're not automatically strict in modifications anymore and you no longer have a guarantee of mutable state, only the strong reason to believe that the compiler will choose that particular optimization; you can't guarantee mutable structures outside of ST or IO, because that's what they're for.

code:

...

Janin posted:

This isn't an example of mutability; Control.Monad.State is actually just a wrapper around (\state -> (result, newState)) -style functions. IO and ST are the only types which support true mutability.

Janin posted:

This isn't an example of mutability; Control.Monad.State is actually just a wrapper around (\state -> (result, newState)) -style functions. IO and ST are the only types which support true mutability.

Also, if you want strict state in a transformer, use Control.Monad.State.Strict.

Zombywuf posted:

So you can only have mutable state by dropping into another language?

Janin posted:

No, you have mutable state by using the IO and ST kinds.

Zombywuf posted:

FTFY

IO is a monad to let you communicate with the world outside Haskell, for example with the FFI. If you are using it for mutable state alone you are simply referencing another language, not making use of Haskell's support for mutable state.

Milotic posted:

Why are you all being over Haskell anyway? It's Haskell. You do it for a term at uni, scrape a pass in functional programming and drat well make sure you never have to apply for a job where you need to use it again in the real world.

I keep my Haskell programming book on my bookshelf as a stark reminder.

Milotic posted:

Janin posted:

Haskell

shrughes posted:

Haskell merely specifies how the program should change state. The state is actually changed by the compiled executable .

Janin posted:

The compiled executable merely specifies how the program should change state. The state is actually changed by the hardware .

shrughes posted:

Real programmers

Contra Duck posted:

Using this phrase is a horror.

shrughes posted:

Real programmers [1] use Haskell in the real world. If you thought Haskell was something to discard after one term, well, you're a bad programmer.

[1] People doing interesting things, those who don't like languages because of Stockholm syndrome.

Milotic posted:

Also "trap sprung" etc.

Milotic posted:

the defined strategic technology path

Janin posted:

Sure, learning Haskell won't get you hired at some lovely 50k/year PHP farm, but that doesn't seem like a problem.

Smugdog Millionaire posted:

This one struck me right in the ego. I'll have you know that I'm a real programmer