**Packages**- base

The Eq class defines equality (==) and inequality (/=). All the basic datatypes exported by the Prelude are instances of Eq, and Eq may be derived for any datatype whose constituents are also instances of Eq.
Minimal complete definition: either == or /=.

Equality

Evaluates its first argument to head normal form, and then returns its second argument as the result.

Evaluate each action in the sequence from left to right, and collect the results.

Evaluate each action in the sequence from left to right, and ignore the results.

option requires argument

no option processing after first non-option

Evaluate each monadic action in the structure from left to right, and ignore the results.

Evaluate each action in the structure from left to right, and ignore the results.

The subsequences function returns the list of all subsequences of the argument.
> subsequences "abc" == ["","a","b","ab","c","ac","bc","abc"]