[Haskell-cafe] ANN: Wheb -- A WAI framework

MigMit miguelimo38 at yandex.ru
Sat Feb 8 09:19:42 UTC 2014

Haskell is itself quite good at removing boilerplate code. In fact, we Haskellers sometimes take pride in writing clean and boilerplate-free code. Forcing us to use metaprogramming undermines our pride. That's why Template Haskell is much more disliked than other forms of metaprogramming — CPP, C++ templates, Lisp macros, Tcl, Forth, etc. It essentially boils down to this: Template Haskell is hated because Haskell itself is so damn good. Of course, if you have a shitty language to start with, then metaprogramming can only be seen as great help.

Personally, I'm opposed to any form of metaprogramming. I prefer simplicity (says the guy who once asked SPJ if we're going to have polymorphic kinds), so I like having abstractions that semantically lie in the problem domain. Metaprogramming constructs, by definition, have their semantics defined in terms of the code they generate. I don't want to think about code. Ideally, I'd prefer not to see any code, but that's not on the plate right now. That's why I don't like metaprogramming, except for C++ templates, they have some sort of beautiful ugliness.

On 08 Feb 2014, at 05:13, Luke Clifton <ltclifton at gmail.com> wrote:

>> I was rather frustrated with the use of Template Haskell as the main entry point for the big framework projects (Yesod, Snap, etc.) 
> Perhaps slightly off topic, but can someone outline why Template Haskell has so much negativity?
> I've used Yesod a bit, and from my limited experience, the TH does a good job at removing a lot of boilerplate code, while still keeping things readable and type safe.
> The main negatives I see are somewhat complicated error messages if you make a mistake, but the issue is usually pretty easy to spot because the TH is pretty simple.
> Is portability an issue? How do the other Haskell compilers go with it?
> Not to detract from your work, I think it's great to have options! I'm just curious.
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