> In functional programming,
> //combinator libraries// refer to a design style that emphasizes bottom-up program construction.
> Such libraries define a few core data types
> and provide //constructors//—functions that create initial objects—and //combinators//—functions that build larger objects from smaller pieces.
> 
> Combinators enable the programmer to use intuitive visual and spatial reasoning
> that’s vastly more powerful than linear language processing.
> As a result, solving problems with combinators feels like playing with lego pieces.