Prolog “or” operator, query

you can ‘invoke’ alternative bindings on Y this way: Note the parenthesis are required to keep the correct execution control flow. The ;/2 it’s the general or operator. For your restricted use you could as well choice the more idiomatic that on backtracking binds Y to each member of the list. edit I understood with …

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What does @@variable mean in Ruby?

A variable prefixed with @ is an instance variable, while one prefixed with @@ is a class variable. Check out the following example; its output is in the comments at the end of the puts lines: You can see that @@shared is shared between the classes; setting the value in an instance of one changes the value for all other instances of that class and …

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No Multiline Lambda in Python: Why not?

Look at the following: Is this a lambda returning (y, [1,2,3]) (thus map only gets one parameter, resulting in an error)? Or does it return y? Or is it a syntax error, because the comma on the new line is misplaced? How would Python know what you want? Within the parens, indentation doesn’t matter to python, so you …

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Python def function: How do you specify the end of the function?

In Python whitespace is significant. The function ends when the indentation becomes smaller (less). Note that one-line functions can be written without indentation, on one line: And, then there is the use of semi-colons, but this is not recommended: The three forms above show how the end of a function is defined syntactically. As for the semantics, in …

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text highlight in markdown

As the markdown documentation states, it is fine to use HTML if you need a feature that is not part of Markdown. HTML5 supports Expand snippet Else you can use span as suggested by Rad Lexus

What does the `and` keyword mean in OCaml?

The and keyword is used either to avoid multiple let (first example, I never use it for this but why not) or for mutually recursive definitions of types, functions, modules… As you can see in your second example : debug calls debugl and vice versa. So the and is allowing that. [EDIT] It bothered me …

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Static Semantics meaning?

Semantics is about meaning. It includes: the static semantics, which is the part that can be ascertained at compile time, including data typing, whether all variables are declared, which declaration applies to which variable in the case of scoping, what their type is, whether functions and methods are called with correct calling sequences, whether assignments …

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What’s the u prefix in a Python string?

You’re right, see 3.1.3. Unicode Strings. It’s been the syntax since Python 2.0. Python 3 made them redundant, as the default string type is Unicode. Versions 3.0 through 3.2 removed them, but they were re-added in 3.3+ for compatibility with Python 2 to aide the 2 to 3 transition.