[Haskell] Nested guards?

Wolfgang Jeltsch g9ks157k at acme.softbase.org
Wed Dec 5 17:12:06 EST 2007

Am Mittwoch, 5. Dezember 2007 00:16 schrieb Per Gundberg:
> Have you looked at the proposed view patterns? It seems like it would
> cover the case you gave here. I don't know if there's work being done in
> this area though.
> http://hackage.haskell.org/trac/ghc/wiki/ViewPatterns
> //Gundberg

I cannot resist citing Henning Thielemann (actually translating from German).  
The following text is from is very good squib about how to become a scripting 
language hater within five days [1].  Please take it with a grain of humor.  
I don’t want to offend anyone.

Here’s the text:

> The root idea of functional programming simplifies many things.  No need to
> distinguish between constants and variables, no “call by reference”, no
> assignments, no predefined loop structures—everything is manageable and the
> effects of functions are controllable.   
> It is clear that this situation must not stay this way.  Bit by bit,
> disciples of Perl and Python discover Haskell and demand that Haskell will
> be plastered with syntactic sugar until the simplicity of the functional
> approach isn’t visible anymore.  Sadly, they seem to be successful with this
> as syntax extensions like parallel list comprehensions show.  
> Many Haskell newcomers don’t seem to bother studying the concept of
> functions and the wide variety of applications of higher order functions.
> They rather avoid everything systematic and construct their programs mainly
> from syntactic sugar like list comprehensions, guards, pattern guards, infix
> operators and do notation, optionally also with pettifogging recursions.
> Because they don’t know anything else, they aren’t tired of emphasizing how
> important such syntactic sugar is.  In addition, the strict order of
> dataflow imposed by functions is attacked again and again.  Yes, global 
> variables are just immortal.           

[1] <http://users.informatik.uni-halle.de/~thielema/ScriptingHater.html>

Best wishes,

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