The Whiteboard

12:35 AM

@RobertHarvey you have to use a generic constraint where T : new()

msdn.microsoft.com/en-us/library/d5x73970.aspx

@RobertHarvey generic constraints hint the compiler that "anytime somebody tries to use this and supply a T that doesn't meet this constraint, fail to compile" - the new() constraint says "The type T must have a public parameterless constructor."

@Dr.Ibb ah but we Haskellers live happily free without intellisense or autocompletion, notepadding Haskell is easy because it takes very little Haskell to complete your program! :)

user55340

1:36 AM

I've tweaked the code-reviews to say "code reviews go over there". Some additional wording might be useful.

user55340

@JimmyHoffa Why use notepad when you could just use ed?

Robert Harvey

3:38 AM

This has to be the dumbest language rule I've ever seen. What were they thinking?

0

Q: Comparing wrapper Integer objects

I am comparing two Integer objects with following code....Why output is "Both integer are not equal..." though I have read somewhere Integer or int will be equal only within range of -128 to 127. Why not 128? Integer i1 = 128; Integer i2 = 128; if(i1!=i2){ System.out.println("Both integ...

user55340

3:57 AM

@RobertHarvey Its a side effect of the Flyweight.

user55340

You shouldn't be using == or != to compare Objects. It just happens that the -128 .. +127 range is part of the Integer cache and when using auto boxing will be drawn from that cache. 128, outside of it, isn't an auto boxed value from the cache and so gets a new object.

user55340

4:14 AM

And as to what they were thinking JLS:

user55340

> If the value p being boxed is an integer literal of type int between -128 and 127 inclusive (3.10.1), or a boolean literal true or false (3.10.3) or a character between '\u0000' and '\u007f' inclusive (3.10.4), then let a and b be the the results of any two boxing conversions of p. It is always the case that a == b

user55340

> Ideally, boxing a primitive value would always yield an identical reference. In practice, this may not be feasible using existing implementation techniques. The rule above is a pragmatic compromise, requiring that certain common values always be boxed into indistinguishable objects. The implementation may cache these, lazily or eagerly. For other values, the rule disallows any assumptions about the identity of the boxed values on the programmer's part. This allows (but does not require) sharing of some or all of these references. Notice that integer literals of type long are allowed,…

user55340

As this was written by Gosling, Joy, and Steele... this is exactly what they were thinking.

Jimmy Hoffa

@MichaelT I know, Ed, man! !man ed

Robert Harvey

4:36 AM

@MichaelT C#'s behavior makes more sense to me. All numerical types are comparable by value, even when using ==. Comparing numerical types by reference is just not ... interesting.

Jimmy Hoffa

5:30 AM

@RobertHarvey all value types are (including any struct you create), the string reference type is the only one which has an == implementation for value

they weren't making a decision in C# about numbers specifically, they just made the decision regarding any value type since an equality comparison makes sense when you have a stack value

as well as in the case of reference types - since they are references it's logical for equality to compare pointers since the memory layout of each object may be different though they have identical "value".

Robert Harvey

6:02 AM

@JimmyHoffa All true.

Thank God I don't have to use Java. I've seen many things in it that I don't like.

durron597

1:03 PM

So of course, I immediately had to link this question to @JimmyHoffa

0

Q: What language is Haskell written in?

Also (besides the title question), is there source code available for different impure Haskell functions like IO? I don't mean the Haskell side of the code, but whatever Haskell implements to do IO.

haskell io

ratchet freak

that is not the only haskell question

2

Q: Relation between objects

For a few weeks I’ve been thinking about relation between objects – not especially OOP’s objects. For instance in C++, we’re used to representing that by layering pointers or container of pointers in the structure that needs an access to the other object. If an object A needs to have an access to...

haskell relationships

durron597

@ratchetfreak There's another one??!

ratchet freak

@durron597 haskell's reach extends far and wide young man

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