On 9/08/2015, at 5:28 am, Hilco Wijbenga
I wholeheartedly agree with replacing the current "type" with "alias",
That would be to replace a precise time with a vague one. All sorts of things can be aliased. Especially when someone writes code that I would like to use, but writes it with an American accent, I would very much like to be able to do things *like* alias Colour = Color and I would like to do this for types, for modules, for constructors, for plain functions, &c. I am not saying that the same *form* of declaration should be used in each case, but that declarations all using the _word_ 'alias' should be available to make it quite plain to the reader what is going on. In particular, there is currently no way to give an additional name to a constructor that lets you *use* it as a constructor. 'alias' is far too potentially useful a word to squander this way. Consider ML: val thingy = 42 This says that 'thingy' is another name for the val(ue) 42. It's an equality for values. type 'a sequence = 'a list This says that for any type 't, 't sequence is another name for the type 't list. It's an equality for types. Type is the *perfect* word here, in ML. Now Haskell does not the 'val' keyword (nor the 'fun' keyword) and it doesn't need them. But it *does* have two kinds of type declaration, one of which *IS* a type equality type Sequence t = [t] and *looks like it*, and one of which ISN'T a type equality. If you want to argue about the grammar of 'data' declarations, go right ahead. I myself was a little confused by them at the beginning, because the declare a new type and some constructors, but do not declare 'data' in the sense that a DATA statement in BASIC or Fortran or the DATA DIVISION in COBOL does. The word 'data' is so very far from conveying the idea "introduce a new type" that it's not funny. But to be confused by 'type' declarations? That's, well, alien. Especially as in the Haskell teaching material I'm familiar with, people are introduced to 'type' declarations doing the utterly familiar 'introduce a new name for an old type' thing before they're introduced to 'data'.
the current "type" is just flat out wrong: it does *not* create a type.
AND IT DOES NOT *CLAIM* TO CREATE A TYPE. It claims to state a type EQUALITY, and it really does. It's just like if you write answer = 42 This does NOT define a new constant. It gives a new name for an existing value. Next thing someone will say that this ought to be written value_alias answer = 42 or something.