On 9/23/11 8:03 PM, Martin Nowak wrote:
On Thu, 22 Sep 2011 22:54:55 +0200, Andrei Alexandrescu
<[email protected]> wrote:
I want to add some points against introducing this particular syntax.
1. Foremost using '=>' is unfamiliar. Comming from C++ or Java you
really have to learn reading it.
If you weighted the lambda syntaxes with the tiobe factor, arrows would
be a minority.
Well the C++2011 lambda syntax is quite foreign for C++ users, too.
How often have you stopped reading about a language because the code
examples were unreadable?
Besides my liking for haskell, I don't want to see anything close to
this on the D site.
mergesortBy less [] = []
mergesortBy less xs = head $ until (null.tail) pairs [[x] | x <- xs]
where
pairs (x:y:t) = merge x y : pairs t
pairs xs = xs
merge (x:xs) (y:ys) | less y x = y : merge (x:xs) ys
| otherwise = x : merge xs (y:ys)
merge xs ys = xs ++ ys
I don't understand the point being made here.
2. D is not a functional language, using the implies arrow in 'a =>
write(1, a.ptr, a.length)' creates a horribly association.
Hackeyed as that sounds, D is a multi-paradigm language and includes a
lot of functional artifacts.
3. I don't see any of the proposed rewrites is working for nullary
delegates.
'=> foo()' ???
Or '_ => foo()' => 'Error can't deduce parameter'.
The comma-separated list may be empty.
4. The expression is badly delimited.
The first rewrite symbol => expression
is actually symbol => expression\{CommaExpression, CatExpression}.
E.g.:
dgs ~= (int a) => (a + 5) ~ (int a) => (a ^^ 2);
foo(a, b => (log(b), b), c)
And that with a pending tuple syntax reclaming even more parens, comma
overloads.
Not sure I understand this point either, sorry.
So D is a curly bracket language.
http://en.wikipedia.org/wiki/List_of_programming_languages_by_category#Curly-bracket_languages
What is wrong the, I think earlier proposed, very simple solution.
http://www.digitalmars.com/d/2.0/expression.html#FunctionLiteral
FunctionLiteral:
function Typeopt ParameterAttributes opt FunctionLiteralBody
delegate Typeopt ParameterAttributes opt FunctionLiteralBody
ParameterAttributes FunctionLiteralBody
FunctionLiteralBody
ParameterAttributes:
Parameters
Parameters FunctionAttributes
FunctionLiteralBody:
FunctionBody
'{' Expression '}'
(a, b) {a+b} // takes the same amount of characters
We've been discussing the issues of this form.
Andrei
