The trick is to use type classes. In the case of printf, the key is the PrintfType type class. It does not expose any methods, but the important part is in the types anyway. class PrintfType r printf :: PrintfType r => String -> r So printf has an overloaded return type. In the trivial … Read more
EDIT: This no longer works. As foreseen in the initial answer, the ABI appears to have changed out from under this answer Played around for a bit and got it to work — Double checked for leaks or abandoned memory and didn’t see any. NSArray *fixedArguments = [[NSArray alloc] initWithObjects: @”foo”, @”bar”, @”baz”, nil]; NSRange … Read more
This has nothing to do with tuples. Anyway, it isn’t possible to convert from an array to a tuple in the general case, as the arrays can have any length, and the arity of a tuple must be known at compile time. However, you can solve your problem by providing overloads: // This function does … Read more
The spread operator in the arrays RFC has been implemented in PHP 7.4: $ary = [3, 4, 5]; return [1, 2, …$ary]; // same as [1, 2, 3, 4, 5] Caveat: The unpacked array/Traversable can only have integer keys. For string keys array_merge() is still required.
I guess it’s related to bug #6886431, which seems to be fixed in OpenJDK 7 as well. The problem is that JLS 15.12.2.5 Choosing the Most Specific Method says that one method is more specific than another one when types of formal parameters of the former are subtypes of formal parameters of the latter. Since … Read more
I’m not an expert in specification reading, but it looks like the varargs Syntax is not supported for anonymous function. Compare the syntax for Function Declaration vs Anonymous Functions in the Language Spec From 4.6 Function Declarations and Definitions ParamType ::= Type | ‘=>’ Type | Type ‘*’ 6.23 Anonymous Functions Binding ::= (id | … Read more
This is called a variable number of arguments or in short varargs. It’s static type is Seq[T] where T represents T*. Because Seq[T] is an interface it can’t be used as an implementation, which is in this case scala.collection.mutable.WrappedArray[T]. To find out such things it can be useful to use the REPL: // static type … Read more
def foo(msf: String, o: AnyRef, os: AnyRef*) = println( String.format(msf, (o :: os.toList).toArray : _* ))
Parameters of functions that correspond to … are promoted before passing to your variadic function. char and short are promoted to int, float is promoted to double, etc. 6.5.2.2.7 The ellipsis notation in a function prototype declarator causes argument type conversion to stop after the last declared parameter. The default argument promotions are performed on … Read more
It follows the C convention. The C convention in turn is based on CPU architectures which pass arguments on the stack. The first non-vararg arguments end up at a fixed offset in the stackframe. If you could put the vararg arguments first, the stack offset of the following arguments would depend on how many vararg … Read more