The Gleam Standard Library

The animator's Gleam code uses the types and functions from Gleam's standard library (gleam_stdlib) listed below. A few others aren't listed because only parser.gleam or the grader's decoding uses them. Each description is the first paragraph of that type or function's documentation; follow its link for the rest, including examples.

These are separate from the built-in functions that a draw function can call, which are listed in A Subset of Gleam.

`gleam/dict`

type Dict: A dictionary of keys and values.
dict.each: Calls a function for each key and value in a dict, discarding the return value.
dict.from_list: Converts a list of 2-element tuples #(key, value) to a dict.
dict.get: Fetches a value from a dict for a given key.
dict.keys: Gets a list of all keys in a given dict.
dict.merge: Creates a new dict from a pair of given dicts by combining their entries.
dict.new: Creates a fresh dict that contains no values.

`gleam/float`

float.random: Generates a random float between the given zero (inclusive) and one (exclusive).
float.truncate: Returns the value as an Int, truncating all decimal digits.

`gleam/int`

int.absolute_value: Returns the absolute value of the input.
int.max: Compares two ints, returning the larger of the two.
int.to_float: Takes an int and returns its value as a float.
int.to_string: Prints a given int to a string.

`gleam/io`

io.println: Writes a string to standard output (stdout), appending a newline to the end.

`gleam/list`

list.append: Joins one list onto the end of another.
list.count: Counts the number of elements in a given list satisfying a given predicate.
list.filter: Returns a new list containing only the elements from the first list for which the given functions returns True.
list.find: Finds the first element in a given list for which the given function returns True.
list.find_map: Finds the first element in a given list for which the given function returns Ok(new_value), then returns the wrapped new_value.
list.flatten: Joins a list of lists into a single list.
list.fold: Reduces a list of elements into a single value by calling a given function on each element, going from left to right.
list.key_find: Given a list of 2-element tuples, finds the first tuple that has a given key as the first element and returns the second element.
list.length: Counts the number of elements in a given list.
list.map: Returns a new list containing the results of applying the supplied function to each element.
list.reverse: Creates a new list from a given list containing the same elements but in the opposite order.
list.try_fold: A variant of fold that might fail.
list.try_map: Takes a function that returns a Result and applies it to each element in a given list in turn.
list.zip: Takes two lists and returns a single list of 2-element tuples.

`gleam/option`

type Option (with constructors None and Some): Option represents a value that may be present or not. Some means the value is present, None means the value is not.

`gleam/result`

result.map: Updates a value held within the Ok of a result by calling a given function on it.
result.map_error: Updates a value held within the Error of a result by calling a given function on it.
result.replace_error: Replace the error within a result
result.try: "Updates" an Ok result by passing its value to a function that yields a result, and returning the yielded result. (This may "replace" the Ok with an Error.)
result.unwrap: Extracts the Ok value from a result, returning a default value if the result is an Error.

`gleam/string`

string.inspect: Returns a String representation of a term in Gleam syntax.
string.join: Joins many Strings together with a given separator.
string.length: Gets the number of grapheme clusters in a given String.
string.pad_end: Pads the end of a String until it has a given length.
string.replace: Creates a new String by replacing all occurrences of a given substring.
string.split: Creates a list of Strings by splitting a given string on a given substring.
string.starts_with: Checks whether the first String starts with the second one.