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Core features for the thx library

README.md

thx.core

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Generic multi-purpose library. thx.core aims to be the lodash library for Haxe.

Data Structures

thx.core provides a few data types to complete the standard library.

AnonymousMap

Wraps an anonymous object in Map<String, T> compatible structure.

var map = new AnonymousMap({ name : "Franco" });

map.get("name"); // "Franco"

The intention of this class is not to encourage anonymous objects as data containers but to simplify the approach to untyped data like JSON results.

Either

Either is a value container. It can contain values from two different types but only one per instance. It can be handy when you want to manage values that can be in one of two possible states. A classic example is a Result where the wrapped value can be either a success or a failure.

typedef MyResult = Either<Error, String>;

var result : MyResult = Left(new Error("something smells"));

var result : MyResult = Right("the answer is 42");

Note that thx.core.Result is an abstract on top of Either with some additional features.

NOTE: Haxe v.3.2.0 introduces its own haxe.ds.Either type. It is 100% compatible with the one provided by thx.core. For that reason, thx.core adopts the official one when available. In the future thx.core.Either will probably be deprecated.

Nil

Nil is a special enum that only contains one constructor nil that takes no parameter. It denotes the absence of a value. It is very handy when you want to work on functions of arity 1 and you don't want to special case them to support an empty list of arguments.

function do<T>(arg : T) { /* do magic */ }

do(nil) { /* ... */ } // use `do` with an empty argument
typedef F<T> = T -> String;

// the following function satisfies the typedef above
function myF(_ : Nil) : String { /* ... */ }

Result

Result is a wrapper (abstract) on top of thx.core.Either. It semantically represents the result of an operation that can either a success or a failure.

var success : Result<String, String> = Right("victory!");

success.isSuccess; // true
success.isFailure; // false
success.value(); // "victory!"
success.error(); // null
success.optionValue(); // Some("victory!")
success.optionError(); // None

var failure : Result<String, String> = Left("oh, no ...");

failure.isSuccess; // false
failure.isFailure; // true
failure.value(); // null
failure.error(); // "oh, no ..."
failure.optionValue(); // None
failure.optionError(); // Some("oh, no ...")

thx.promise.Future always bring a result and thx.promise.Promise extend the concept by adding the possibility of a failure.

Set

A Set is a list of unique values. Values are unique in a way that no duplicates can exist in the same Set. Note that uniqueness is enforced by strict phisical equality. That means that is perfectly possible to have a Set of class instances where the instances contain exactly the same values but are referring different objects. Primitive values like Int, Float, String do not incur in such cases.

Set<T> is an abstract built on top of Array<T>. Like Array, it is a mutable structure and shares with it most of its methods with.

var set = Set.create();
set.add(1);
set.add(2);
set.add(3);
// again one!
set.add(1);

set.length == 3; // true!

A Set can be easily created from an Array:

var s : Set<Int> = [1,2,3,1]; // note that the repetead value will be removed

Set supports boolean operations like union, intersection and difference:

var s = ([1,2,3] : Set<Int>).union([2,3,4]).difference([2,3]);
// s contains [1,4]

Note that boolean operations return new Set instances and do not change the original instances.

Tuple

A Tuple is a value containing multiple values of potentially different types. All tuples are immutable; that means that any tuple operation that seems to change the Tuple it is creating a new structure instead.

A Tuple0 contains no value and it is equivalent to thx.core.Nil.nil.

A Tuple1 contains one value and it is a wrapper to the value type itself.

A Tuple2, the most conventional of the tuples, is an abstract wrapper around an object of type { _0 : T0, _1 : T1 }.

var t = new Tuple2("thx", 1);
t._0; // "thx", same as t.left
t._1; // 1, same as t.right

t.flip().left; // `flip` inverts the terms of the tuple and `left` is now 1

t.dropRight(); // return a Tuple1 which in this case results in "thx"

t.with("0.123") // appends a new value to the right creating a new Tuple3

Tuple3, Tuple4, Tuple5 and Tuple6 work much like Tuple but bring more values.

Type Helpers

thx.core also contains a lot of useful helper classes to simplify dealing with a lot of types from the standard library.

Most methods described below assume that the respective types have been required using using and are used as type extensions.

Arrays/Iterators/Iterables

Similarly to Lambda, Arrays/Iterators/Iterables provide extension methods to work with collections. They share most of the methods and are repeated to avoid useless casting or conversions and to provide optimizations where possible.

Some examples of the common features:

[1,2,3].all(function(i) return i > 1); // false
[1,2,3].any(function(i) return i > 1); // true

// filter works for any Iterator/Iterable like the normal Array.filter
[1,2,3].filter(Ints.isOdd); // [1,3]

[1,2,3].filterPluck(_ != 2); // equivalent to [1,2,3].filter(function(i) return i != 2)

[1,2,3].isEmpty(); // false

[1,2,3].pluck(_ * 2); // [2,4,6]

Arrays

Beside the usual methods to traverse, reduce, slice and arrange arrays, Arrays contains peculiar things like:

  • compact to filter out null values
  • cross to create cross products between 2 arrays
  • equals to compare each element of two arrays
  • flatMap and flatten to reduce nested arrays into flat arrays
  • groupBy to create Map from arrays
  • sample and sampleOne to extract random elements from one array
  • shuffle to reorder randomly an array
  • zip/unzip to create/deconstruct arrays of Tuple

In the thx.core.Arrays module are also defined a few specialized operations for specific type of arrays: ArrayFloats, ArrayInts and ArrayStrings. The numeric array variations provide methods for average, sum, min and max (plus compact for Float that removes non-finite numbers).

Iterators

it.isIterator() // checks that the instance has the right members to be an Iterator

Iterables

it.isIterable() // checks that the instance has the right members to be an Iterable

Floats

Floats contains extension methods to work with Float values. Some examples:

  • canParse checks if a string can be safely parsed into a Float. Use parse for the final conversion
  • clamp restricts a value within a given range
  • compare returns a value suitable for comparison
  • interpolate does exactly that :)
  • nearEquals compare two values with a small margin to account for floating precision issues
  • wrap ensure that the passed valeu will be included in the boundaries. If the value exceeds max, the value is reduced by min repeatedely until it falls within the range. Similar and inverted treatment is performed if the value is below min

Functions

Extension methods for functions. Methods are roughly distributed between Functions, Functions0, Functions1, Functions2 and Functions3 where the number suffix denotes the arity (number of arguments) of the function that are going to be extended.

  • after returns a function that wraps the passed function. The original function will be executed only after it has been called n times
  • compose returns a function that calls the first arguemnt function with the result of the following one.
  • equality performs strict physical equality
  • identity is a function that returns its first argument
  • join creates a function that calls the 2 functions passed as arguments in sequence
  • memoize returns a new version of the argument function that stores the computation from the function and recycles it whenever called again
  • negate return a new version of a function that returns a Bool and transforms it so that it will return the negation of its result
  • noop its a function that performs no computations and doesn't return a value
  • once wraps and returns the argument function. once ensures that f will be called at most once even if the returned function is invoked multiple times
  • times creates a function that calls callback n times and returns an array of results.

Ints

Extension methods for integer values. Many methods are implemented the same as in thx.core.Floats but specialized for Int values. Some are methods available in Std or Math but only available for Float.

Maps

Extension methods for Maps.

  • tuples transforms a Map<TKey, TValue> in an Array of Tuple2<TKey, TValue>
  • mapToObject transforms a Map<String, T> into an anonymous object.

Objects

Extension methods for objects.

  • isEmpty returns true if the object contains no fields
  • objectToMap transform an object in to a map of type Map<String, Dynamic>
  • size counts the number of fields in an object
  • values returns an array with the values of each field (order is not guaranteed)
  • tuples returns an array of Tuple2<String, Dynamic> containing pairs of fields/values (order is not guaranteed)

Options

Extension methods for the haxe.ds.Option type.

  • equals campares two Option values of the same type
  • flatMap reduces an Option<T> value into an Array<T>
  • map transforms a value contained in Option<T> to Option<TOut>
  • toArray transforms an Option value to an Array
  • toBool transforms an Option to true (Some(_)) or false (None)
  • toOption transforms any type T into Option<T>
  • toValue extracts the value from Option or returns null

Nulls

Nulls provides extension methods that help to deal with nullable values.

  • isNull checks if a chain of identifier is null at any point
  • notNull is the negation of isNull
  • opt traverses a chain of dot/array identifiers and it returns the last value in the chain or null if any of the identifiers is not set
  • or is like opt but allows an alt value that replaces a null occurrance
var s : String = null;
trace(s.or('b')); // prints 'b'
s = 'a';
trace(s.or('b')); // prints 'a'

// or more complex
var o : { a : { b : { c : String }}} = null;
trace((o.a.b.c).or("B")); // prints 'B'
var o = { a : { b : { c : 'A' }}};
trace((o.a.b.c).or("B")); // prints 'A'

Note that the parenthesis wrap the entire chain of identifiers. That means that a null check will be performed for each identifier in the chain.

Identifiers can also be getters and methods (both are invoked only once and only if the check reaches them). Python seems to struggle with some native methods like methods on strings.

Strings

Extension methods for String. Some examples:

  • after returns the text after the first occurance of a certain string
  • capitalizeWords each word in a text
  • collapse trims white spaces from the beginning/end of a text and reduces any sequence of more than white space to just one inside a given text
  • isAlphaNum returns true if the text contains only alpha-numeric characters
  • ifEmpty returns the either the passed value if not empty (null or "") or an alternative value.
  • isDigitsOnly returns true if the string contains only digits
  • map iterates on each character individually
  • repeat creates a string repeating a certain pattern n times
  • stripTags sanitize html string by removing any tag-like information
  • wrapColumns breaks a long string into consistently sized lines without breaking words apart.

Strings also defines a type alias to StringTools. This way by including it, you also get all the StringTools extension methods:

using thx.core.Strings;

Dates

Extension methods for Date and Floats that represent date values.

Some examples:

  • compare to sort Date values.
  • isLeapYear/isInLeapYear to find leap year about a spefici year or date.
  • numDaysInMonth/numDaysInThisMonth return the number of days in a month for a specified date.
  • snapTo/snapPrev/snapNext to force a date value to a close boundary (Minute, Hour, Day, Week, Month, Year).
  • jump/prevX/nextX to skip forward/backward by a given time delta.

Dates also defines a type alias to DateTools. This way by including it, you also get all the DateTools extension methods:

using thx.core.Dates;

Types

Extension methods to use on values, types and classes.

isAnonymousObject returns true if the passed argument is an anonymous object.

Types.isAnonymousObject({}); // true

valueTypeToString returns a string describing the type of any value.

Types.valueTypeToString("thx"); // "String"
Types.valueTypeToString(1); // "Int"
Types.valueTypeToString(Left("some")); // "thx.core.Either"

valueTypeInheritance returns an array of string describing the entire inheritance chain of the passed value.

valueTypeInheritance works on any value, not just class instances. Obviously most types will return an array of just one value.

class B extends A {};

Types.valueTypeInheritance(new B()); // ["B", "A"]

Dynamics.equals

Compares any two values checking their type first and recursively all their members for structural equality. It should work on any type. If the values passed are objects and they contain a method equals, it will be used to decide if the two objects match.

Dynamics.equals({ a : 1 }, { a : 1 }); // true
Dynamics.equals(1, 2); // false

ERegs.escape

It escapes any characer in a string that has a special meaning when used in a regular expression.

General Purpose Features

The following utilities have no direct relationship with standard types and just provides commonly required functionalities.

Timer

Timer provides several meaning to delay the execution of code. At the moment it is only implemented for platforms that have a native concept of Timer like Swf and JavaScript or c++/Neko with OpenFL or NME.

All of the Timer methods return a function with signature Void -> Void that can be used to cancel the timer.

// set the execution delayed by 200ms
var cancel = Timer.delay(doSomethingLater, 200);

// cancel immediately (`doSomethingLater` will never be executed)
cancel();

Note that calling the cancel function multiple times have no effect after the first execution.

UUID

Helper class to generate UUID strings (version 4).

UUID.create(); // generates something like f47ac10b-58cc-4372-a567-0e02b2c3d479

Errors

Haxe brings the power of being able to use any type to throw an exception. It is not uncommon to find code that simply does throw "my error. There is nothing wrong with that approach except that some times, most commonly in bigger applications that use many libraries, you need to be conservative when you want to catch an exception and introduce a catch(e : Dynamic) to be sure to not forget any possible error. The problem with Dynamic is that you don't really know how to access the error info. The type thx.core.Error described below tries to solve this problem providing a common and generic implementation.

Error

Represent a Runtime error or exception. When used with JS it inherits from the native Error type. It tries to bring information like error message and error location. Usage is super easy:

throw new Error('my error message');

Note that Error will try to collect (if possible) information about the error stack and the error location using haxe.PosInfos.

On top of thx.core.Error a few definitions are built for very common situations.

AbstractMethod

Mark a method as abstract. If it is not implemented by a sub-type a runtime exception is thrown indicating the class/method name that is abstract and has no implementation.

function myAbstract() {
    throw new AbstractMethod(); // no argument required
}

NotImplemented

Similarly to AbstracMethod it is used to mark method that have not been implementd yet.

function myNotImplemented() {
    throw new NotImplemented(); // no argument required
}

NullArgument

Checks that a certain argument of a function is not null and throws an exception otherwise.

function myMethod(value : String) {
    NullArgument.throwIfNull(value);
}

With arguments of type Array, String, Iterator or Iterable, it is also possible to check for emptyness:

function myMethod(value : String) {
    NullArgument.throwIfEmpty(value); // check that value is not `null` but also not empty ("")
}

Macro Helpers

Macros

Helper methods to use inside macro context.

MacroTypes

Several utility function to extract type information from macro types and expressions.

Install

From the command line just type:

haxelib install thx.core

To use the dev version do:

haxelib git thx.core https://github.com/fponticelli/thx.core.git
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