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What does “abstract over” mean?

...mbers under a single symbol ns: def sumOf(ns: List[Int]) = ns.foldLeft(0)(_ + _) And we don't particularly care that it's a List either. List is a specific type constructor (takes a type and returns a type), but we can abstract over the type constructor by specifying which essential characteristi...
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How to pass values between Fragments

...uper.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (findViewById(R.id.container) != null) { if (savedInstanceState != null) { return; } getFragmentManager().beginTransaction() ...
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What should I name a table that maps two tables together? [closed]

...oducts and another category for recipe. for both tables we will have recipe_categories and product_categories, and since we can't just "categories" table name for both tables, in order to prevent the conflict, the junction tables for product and recipe will be "recipe_recipe_categories" and "product...
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How to properly create composite primary keys - MYSQL

...is a gross oversimplification of an intense setup I am working with. table_1 and table_2 both have auto-increment surrogate primary keys as the ID. info is a table that contains information about both table_1 and table_2 . ...
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How do I check in JavaScript if a value exists at a certain array index?

...his answer: stackoverflow.com/a/39171620/3120446 – dx_over_dt Jul 9 '19 at 20:19  |  show 9 more comments ...
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How to convert an array to object in PHP?

...son Medina pointed out, a really clean solution is to use the built-in json_ functions: $object = json_decode(json_encode($array), FALSE); This also (recursively) converts all of your sub arrays into objects, which you may or may not want. Unfortunately it has a 2-3x performance hit over the loop...
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Convert string to integer type in Go?

...64); err == nil { fmt.Printf("i=%d, type: %T\n", i, i) } var i int if _, err := fmt.Sscan(s, &i); err == nil { fmt.Printf("i=%d, type: %T\n", i, i) } Output (if called with argument "123"): i=123, type: int i=123, type: int64 i=123, type: int Parsing Custom strings There is also a...
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Python nonlocal statement

...so that it looks more like the idioms of languages with closures. def make_counter(): count = 0 def counter(): nonlocal count count += 1 return count return counter Obviously, you could write this as a generator, like: def counter_generator(): count = 0 ...
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How to create streams from string in Node.Js?

... to wrap the string in an array. https://nodejs.org/api/stream.html#stream_stream_readable_from_iterable_options share | improve this answer | follow | ...
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How do I get a file extension in PHP?

...t few people know it. Meet pathinfo(): $ext = pathinfo($filename, PATHINFO_EXTENSION); This is fast and built-in. pathinfo() can give you other information, such as canonical path, depending on the constant you pass to it. Remember that if you want to be able to deal with non ASCII characters, y...