[Haskell-cafe] Line noise

Mads Lindstrøm mads_lindstroem at yahoo.dk
Sun Sep 21 16:30:08 EDT 2008

Andrew Coppin wrote:

> Idiomatic Haskell seems to consist *only* of single-letter variable 
> names. When did you last see a pattern like (customer:customers)? No, 
> it'd be (c:cs), which isn't very self-documenting. Ditto for type 
> variables by the way. (Map k v, anyone?) It also seems to be Haskell 
> convention to use "a" as a type variable; personally I always use "x". I 
> guess that's the algebra in my blood or something...

The more abstract (generic) thing gets, the less likely you will be able
to find a telling name. And if you cannot find a telling name, you can
just as well make it short. And as Haskell is more abstract, we get more
short identifiers. E.g. in your earlier sorting function:

  qsort (x:xs) = ...

what would you propose to call the elements? Yes, if it sorted
customers, you call 'em (customer:customers). But you have made a very
abstract sorting function, which sorts a lot besides customers. And then
you are bound to end up with a non-telling name.

However, I will grant you that Map k v, could have used longer type
variables. But we are not alone with using one letter type variable
names http://java.sun.com/javase/6/docs/api/java/util/HashMap.html . And
frankly, in this specific case, I think most programmers (Haskell or
non-Haskell) will be able to guess what k and v means, when they are
standing right after Map.



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