Documentation for gololang.StandardAugmentations

This module defines the set of standard augmentations.

Augment functions to make them behave more like objects from java.util.function

Alias for FunctionReference::invoke

Alias for FunctionReference::invoke

Call this function with no arguments.

Augmentations for Golo tuples.

Filters elements using a predicate, returning a new tuple.

Returns the first element that satisfies a predicate, or null if none matches.

Joins the elements of a tuple into a string and using a separator.

Maps the elements of a tuple, and returns a tuple with the transformed values.

Augmentations over CharSequence to view it as a “real” char collection.

Returns the first char of the sequence, of null if empty.

Checks if the sequence is empty.

Returns the remaining subsequence as a String (i.e. an immutable sequence)

Augmentations over iterable collections.

Counts the number of elements that satisfy a predicate:

println([1, 2, 3, 4]: count(|n| -> (n % 2) == 0))

• this: an iterable.
• pred: a predicate function, taking an element and returning a boolean.

Applies a function over each element:

[1, 2, 3]: each(|e| -> println(e))

• this: an iterable.
• func: the function to apply, taking the current element as a parameter.

Checks whether any element satisfied a predicate:

println([1, 2, 3, 4]: exists(|n| -> n > 3))

• this: an iterable.
• pred a predicate function, taking an element and returning a boolean.

General purpose reducing operation:

let data = [1, 2, 3, 4, 5]
println("sum = " + data: reduce(0, |acc, next| -> acc + next))

• this: an iterable.
• initialValue: the initial accumulator value for the reducing operation.
• func: the function to apply over an accumulator and the next value.

Number augmentations.

Similar to upTo, except that the interval iteration is made from high down to low.

Repeats a function many times, as in:

3: times(-> println("Hey!")
4: times(|i| -> println(i))

• count: how many times the func function must be repeated.
• func: a function to execute.

The func function may take 0 or 1 argument. In the later case the argument is the iteration count index.

Repeats a function over a discrete interval:

1: upTo(3, -> println("Hello"))
1: upTo(3, |i| ->println(i))

• low: the start value (inclusive).
• high: the end value (inclusive).
• func: the function to execute.

As in the case of times, func may take an optional index parameter. See also downTo.

Useful string augmentations.

Convenience wrapper over java.lang.String.format(...).

Wrapper over java.lang.Integer.parseDouble.

Wrapper over java.lang.Integer.parseFloat.

Wrapper over java.lang.Integer.parseInt.

rapper over java.lang.Integer.parseInt.

Wrapper over java.lang.Integer.parseLong.

Java collections augmentations.

Destructuration helper.

• return a tuple of the values

Returns an empty collection of the same type as this.

Java lists augmentations.

Appends an element to a list.

Appends a variable number of arguments to a list.

• head: an element to append.
• tail: a variable number of elements to append.

Filters elements based on a predicate:

println(list[1, 2, 3, 4]: filter(|n| -> (n % 2) == 0))

• this: a list.
• pred: a predicate function taking an element and returning a boolean.

filter returns a new collection of the same type as the original one, hence the original list is kept intact.

Finds the first element of a list matching a predicate:

println(list[1, 2, 3, 4]: find(|n| -> n > 3))

• this: a list.
• pred: a predicate function taking an element and returning a boolean.

find returns null when no element satisfies pred.

Returns a list first element, of null if empty.

Inserts an element at some index.

Join the elements into a string:

println(list[1, 2, 3]: join(", "))

• this: a list.
• separator: the element separator string.

The returned string is "" when the list is empty.

Returns a list last element.

Maps elements of a list using a function:

println(list[1, 2, 3]: map(|n| -> n * 10))

• this: a list.
• func: a transformation function.

map returns a new list with the same type, keeping the original list intact.

Sorts the list elements and returns the list.

Sorts the element using a comparator, see java.util.Collections.sort(...).

Returns a new list where the elements have been sorted.

Returns a new list where the elements have been sorted using a comparator. See java.util.Collections.sort.

Prepends an element to a list.

Prepends a variable number of arguments to a list.

Removes the element at the specified position.

This method has the same behaviour as java.util.List.remove(int), but is needed since for Golo everything is an Object and remove is overloaded.

Reverse the elements of the list and returns the list.

See also reversed.

Same as reverse, but the returned list is a new one, leaving the original list order intact.

Returns the rest of a list after its head, as an unmodifiable list.

Convenience wrapper over java.util.Collections.unmodifiableList.

Augmentations over maps.

Adds a tuple [key, value] or a map entry and returns the map.

Alias for put that returns the map.

Adds an element to the map only if there is no entry for that key.

• this: a map.
• key: the element key.
• value: the element value or a function to evaluate to get a value.

The fact that value can be a function allows for delayed evaluation which can be useful for performance reasons. So instead of:

map: addIfAbsent(key, expensiveOperation())

one may delay the evaluation as follows:

map: addIfAbsent(key, -> expensiveOperation())

addIfAbsent returns the map.

Counts the number of elements satisfying a predicate.

Alias for remove that returns the map.

Iterates over each entry of a map.

func takes 2 arguments: the entry key and its value.

Returns true if there is any value satisfying pred, false otherwise.

Filters elements using a predicate, and returns a new map.

pred takes 2 arguments: a key and a value, and returns a boolean.

Returns the first element that satisfies a predicate, or null if none matches.

pred takes 2 arguments: a key and a value, and returns a boolean.

Returns a value from a key or a default value if the entry is not defined.

• this: a map.
• key: the key to look for.
• replacement: the default value, or a function giving the default value.

As it is the case for addIfAbsent, one can take advantage of delayed evaluation:

println(map: getOrElse(key, "n/a"))
println(map: getOrElse(key, -> expensiveOperation())

Note that replacement yields the return value also when there is an entry for key but the value is null.

Maps entries of the map using a function.

func takes 2 arguments: a key and a value. The returned value must have getKey() and getValue() to represent a map entry. We suggest using the predefined mapEntry(key, value) function as it returns such object.

Returns a new empty map of the same type.

Reduces the entries of a map.

func takes 3 arguments:

• an accumulator whose initial value is initialValue,
• a key for the next entry,
• a value for the next entry.

Wrapper for java.util.Collections.unmodifiableMap(...).

Destructurate a map entry in key and value

Convert then entry into an array containing the key and the value.

Augmentations over set collections.

Alias for remove that returns the set.

Excludes a variable number of elements, and returns the set.

Filters the elements using a predicate, and returns a new collection.

Finds the first element that satisfies a predicate pred, and returns it, or null if no element matches.

Alias for contains.

Alias for contains over a variable number of elements.

Alias for add that returns the set.

Includes a variable number of elements, and returns the set.

Transform each value using the func function, and returns a new set.

Convenience wrapper for java.util.Collections.unmodifiableSet(...).