ucg/docsite/site/content/stdlib/functional.md

+++ title = "Functional operations" weight = 5 sort_by = "weight" in_search_index = true +++

UCG comes with some builtin functional operations.

Useful functions

• identity - the Identity function. Returns it's argument unchanged.

Maybe module

Maybe is a monadic style wrapper for values that might be NULL. It provides a several operations for the wrapped value.

• do(op) - runs op which is a function of one argument against the wrapped value if it is not null. Returns the result or NULL wrapped in another maybe.
• or(op) - runs op which is a function of no arguments if the wrapped value is null. Returns the result wrapped in another maybe.
• is_null() - returns true if the wrapped value is null, false otherwise.
• unwrap() - returns the wrapped value
• expect(msg) - returns the wrapped value if it is not null. Throws a compile error with the user provided message otherwise.

let maybe = import "std/functional.ucg".maybe;

let result = maybe{val=NULL}.or(func () => "foo").do(func(v) => v + "bar");
result == "foobar";