What features must a language have for it to be considered a dynamically typed language
Values have types, but variables do not.
Related
C++, Java and Javascript, and Python and Ruby all have different semantics regarding parameter passing.
C++ gives users the choice of passing by reference and value with "&" syntax. Java and Javascript pass by value of reference for objects, and value for primitives. Python and Ruby has its pass by "name and object" semantics, out of a lack of better terminology. Other languages I'm less familiar with, I'm sure, have more semantic categories to throw into the mix.
This is all understandable, but appears somewhat arbitrary as just facts-to-memorize without understanding how the different semantics derive from the design philosophy of the respective languages.
What design decisions or historical background motivate the different parameter passing semantics in each of these languages?
I'm reading the ECMAScript 5.1 Specification but I'm stuck with the following sentence:
Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation.
If they do not necessarily correspond to any specific entity, what do they correspond? I mean a specification type value belongs to the set of specification type values (obviously), so what does that sentence want to say?
The ECMAScript spec describes how the language should behave from the standpoint of a script executing within a conforming environment. It does not describe how that environment should be implemented, just how the script running inside it should work given a set of inputs.
The first part of that sentence is important to the context here:
A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types are Reference, List, Completion, Property Descriptor, Property Identifier, Lexical Environment, and Environment Record.
So the "specification type" in the quote you posted:
Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation.
is one of those types, like "Reference" or "Property Identifier".
The point that this is trying to get across is that your implementation is free to implement these concepts however it pleases. There is no requirement that your implementation have some object that represents a "Reference" type, or some object that represents "Completion" or any of the others. As long as, from the standpoint of a script running on your implementation, things look correct, you are free to implement the language however you please.
This may be a stupid question, but I have no way of testing this with multiple languages.
I am wondering if the Microsoft Translator translates the list of supported languages into the language detected by the browser? I assume is does, but would appreciate validation.
TIA
GetLanguagesForTranslate() returns the set of supported languages IDs.
GetLanguageNames() takes an array of languag IDs and returns the friendly name of the language in the language you specify in the "locale" parameter, where locale is the ISO639 language code.
You may listen to the browser's accept-language setting and pass the first element of it to the locale parameter. That's what the Bing Translator home page does (www.bing.com/translator)
I came across dynamically typed python, statically typed f#, strongly typed C++ and weakly typed JavaScript.
I do not yet know exact differences between all these type systems. In general, I could figure out that Strong typing is associated with static typing, and weak typing is associated with dynamic typing.
Can somebody explain each type systems with examples.
Python is dynamically, strongly typed. Types cannot be arbitrarily, implicitly converted from one to another, and names can be bound to objects of any type.
PHP is dynamically, weakly typed. Certain types will be implicitly converted if appropriate, and variables can be assigned any type.
Java is statically, strongly typed. Types cannot be converted except up their inheritance or interface hierarchy, and variables can only be assigned subclasses or implementing objects.
C is statically, weakly typed. Certain types can be converted when convenient (e.g. char and int), and variables can only contain the type they are declared as.
DSLs improve code readability and expressiveness and more importantly give a significant level of abstraction..
You can agree that regular expressions, once you have mastered them , text processing becomes easy in any programming language you will learn.
What domain specific language have you used that you feel should be standardized across all languages?
Mathematics
A standard notation for lambda expressions would be nice.
I am particularly enamored with Groovy's XmlSlurper as a "good" language syntax for XML:
facilitates XPath-ish (i.e. GPath) statements
direct access to nodes and attributes using simple dot notation syntax as opposed to "getNode()" or "getAttribute()" API calls.