Tutorial by Examples: i

You can store the signing information setting environment variables. These values can be accessed with System.getenv("<VAR-NAME>") In your build.gradle you can define: signingConfigs { release { storeFile file(System.getenv("KEYSTORE")) storePasswo...

We use the null function to check if a given Map is empty: > Map.null $ Map.fromList [("Alex", 31), ("Bob", 22)] False > Map.null $ Map.empty True

There are many querying operations on maps. member :: Ord k => k -> Map k a -> Bool yields True if the key of type k is in Map k a: > Map.member "Alex" $ Map.singleton "Alex" 31 True > Map.member "Jenny" $ Map.empty False notMember is similar: &g...

Inserting elements is simple: > let m = Map.singleton "Alex" 31 fromList [("Alex",31)] > Map.insert "Bob" 99 m fromList [("Alex",31),("Bob",99)]

> let m = Map.fromList [("Alex", 31), ("Bob", 99)] fromList [("Alex",31),("Bob",99)] > Map.delete "Bob" m fromList [("Alex",31)]

The Data.Map module in the containers package provides a Map structure that has both strict and lazy implementations. When using Data.Map, one usually imports it qualified to avoid clashes with functions already defined in Prelude: import qualified Data.Map as Map So we'd then prepend Map funct...

In Normal Mode, commands can be entered by direct key combinations (typing u to undo the last change, for example). These commands often have equivalents in 'ex' mode, accessed by typing a colon :, which drops you into a single-line buffer at the bottom of the Vim window. In 'ex' mode, after typing...

Undo Command:Descriptionuu,undoUndo the most recent change5uUndo the five most recent changes (use any number) Please be aware that in Vim, the 'most recent change' varies according to the mode you are in. If you enter Insert Mode (i) and type out an entire paragraph before dropping back to Normal...

sqlite> SELECT TYPEOF(NULL); null sqlite> SELECT TYPEOF(42); integer sqlite> SELECT TYPEOF(3.141592653589793); real sqlite> SELECT TYPEOF('Hello, world!'); text sqlite> SELECT TYPEOF(X'0123456789ABCDEF'); blob

For booleans, SQLite uses integers 0 and 1: sqlite> SELECT 2 + 2 = 4; 1 sqlite> SELECT 'a' = 'b'; 0 sqlite> SELECT typeof('a' = 'b'); integer > CREATE TABLE Users ( Name, IsAdmin ); > INSERT INTO Users VALUES ('root', 1); > INSERT INTO Users VALUES ('john', 0); > S...

SQLite uses dynamic typing and ignores declared column types: > CREATE TABLE Test ( Col1 INTEGER, Col2 VARCHAR(2), -- length is ignored, too Col3 BLOB, Col4, -- no type required Col5 FLUFFY BUNNIES -- use whatever you want ); > ...

You define a keyword argument in a method by specifying the name in the method definition: def say(message: "Hello World") puts message end say # => "Hello World" say message: "Today is Monday" # => "Today is Monday" You can define multip...

2.1 Required keyword arguments were introduced in Ruby 2.1, as an improvement to keyword arguments. To define a keyword argument as required, simply declare the argument without a default value. def say(message:) puts message end say # => ArgumentError: missing keyword: message say ...

You can define a method to accept an arbitrary number of keyword arguments using the double splat (**) operator: def say(**args) puts args end say foo: "1", bar: "2" # {:foo=>"1", :bar=>"2"} The arguments are captured in a Hash. You can manip...

C++17 A storage class specifier that hints to the compiler that a variable will be heavily used. The word "register" is related to the fact that a compiler might choose to store such a variable in a CPU register so that it can be accessed in fewer clock cycles. It was deprecated starting ...

A keyword that is part of certain integer type names. When used alone, int is implied, so that signed, signed int, and int are the same type. When combined with char, yields the type signed char, which is a different type from char, even if char is also signed. signed char has a range that inclu...

A type specifier that requests the unsigned version of an integer type. When used alone, int is implied, so unsigned is the same type as unsigned int. The type unsigned char is different from the type char, even if char is unsigned. It can hold integers up to at least 255. unsigned can also be ...

SQLite has no separate data type for date or time values. ISO8601 strings The built-in keywords CURRENT_DATE, CURRENT_TIME, and CURRENT_TIMESTAMP return strings in ISO8601 format: > SELECT CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP; CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP --------...

The static storage class specifier has three different meanings. Gives internal linkage to a variable or function declared at namespace scope. // internal function; can't be linked to static double semiperimeter(double a, double b, double c) { return (a + b + c)/2.0; } // exported to c...

This is very similar to using an Application subclass and overriding the attachBaseContext() method. However, using this method, you don't need to override attachBaseContext() as this is already done in the MultiDexApplication superclass. Extend MultiDexApplication instead of Application: package...