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+++ 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";