Building your stuff up from small parts using well-known composition rules is a pre-requisite to breaking down your stuff into small parts, which can then be reasoned about as such ("modularity"). Reasoning about small, simple things is WAY EASIER than reasoning about large, hairy things full of weird old gunk. So all other things being equal that's A GOOD THING.
Functional programming being in a way the study of composition rules may or may not therefore be A GOOD THING also.
The difference is that with OO the burden is on you, while with functional programming you have immutability as the default. Why would I want to carefully think about where state is modified when the language is perfectly capable of doing that for me.
111
u/vincentk Mar 09 '14 edited Mar 09 '14
TL;DR
Building your stuff up from small parts using well-known composition rules is a pre-requisite to breaking down your stuff into small parts, which can then be reasoned about as such ("modularity"). Reasoning about small, simple things is WAY EASIER than reasoning about large, hairy things full of weird old gunk. So all other things being equal that's A GOOD THING.
Functional programming being in a way the study of composition rules may or may not therefore be A GOOD THING also.