[Haskell-cafe] Re: Comments from OCaml Hacker Brian Hurt

Robert Greayer robgreayer at yahoo.com
Sun Jan 18 11:02:55 EST 2009

----- Original Message ----
From: Andrew Coppin <andrewcoppin at btinternet.com>
> Which is why I personally prefer HiddenTypeVariables. (This has the advantage of using only pronouncible English 
>words, which means you can use it when speaking out loud.)

Existential  - English, easy to pronounce
Quantify - English, easy to pronounce

I know I've been seeing those backwards E's and upside down A's in not-so-advanced Maths courses for a long time (since high school, I'm sure) and I certainly encountered them before 'Boolean'.  If you could do a geometry proof in high school, you have the Maths background need to understand the ideas.  (How they apply to types is another story, but the words shouldn't be scary.)

>> I can't await the next Haskell standard, where at last all those
> extensions are builtin.

> This frightens me.

> At the moment, I understand how Haskell 98 works. There are lots of extensions
> out there, but I don't have to care about that because I don't use them. If I read 
> somebody else's code and it contains a LANGUAGE pragma, I can immediately
> tell that the code won't be comprehendable, so I don't need to waste time trying 
> to read it. But once Haskell' becomes standard, none of this holds any more.
> Haskell' code will use obscure lanuage features without warning, and unless I 
> somehow learn every extension in the set, I'll never be able to read Haskell
> again! (One presumes that they won't add any extensions which actually *break* 
> backwards compatibility, so hopefully I can still pretend these troublesome
> extensions don't exist when writing my own code...)

Some of the most useful libraries (e.g. parsec, generics) use these type system extensions (higher rank polymorphism, existentials).  It would be great if these could be considered 'standard Haskell'.

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