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In Clojure, first and rest apply to sequences, which are a logical list abstraction. They apply to lists, but they can also be used on sequential views of index

In Clojure, first and rest apply to sequences, which are a logical list abstraction. They apply to lists, but they can also be used on sequential views of indexed vectors, maps, sets, database result sets, files in a dir, lines in a file, and an open world of "things that can be seen in some order". head and tail I suspect are much more tied to linked lists and data structure than the more plain first and rest.

namibj 7y ago
I might add that breaking the naming away (from traditions) also helps breaking the mindset away (from "that's how we always did it"). This allows for unified abstract views on things normally distinguished from each other by words, syntax, conventions and mind. This allows stuff like pattern matching generic functional code like the mighty monad with it's transformer. Learning functional programming incl. higher kinded types (dependent types and such) isn't easy for someone used to e.g. Java,C,C++,Python,Go, and others I can't judge of the top of my head. If you ask yourself why said functional is beneficial, remember the popularity and typical confusion of the Monad posts/articles. You might not quite understand / "get" it, but they keep coming up and the authors seem intelligent. So you (might) just have a case of the Blub Paradox[0]. You need to understand it to grok it's usefulness/desirability. [0]: http://www.paulgraham.com/avg.html http://www.paulgraham.com/avg.html
lonelappde 7y ago
If you are using first and rest, then you are treating whatever sequence you have as a linked list, so you've already lost the plot.
- greggyb 7y ago
  You can treat any collection or data structure that implements the sequence protocol as a lazy sequence with (seq collection) But you don't have to. If you choose to, you're not tied to a representation of mutable cons cells. There are good reasons to want to iterate over values in a map or a set, while still wanting the lookup characteristics of those collections, rather than a linked list. This is hardly a controversial stance. Python, for example, supports iteration over many of its data structures and it is recommended to implement the dunder methods for iteration on any class that might reasonably be the basis of an iteration. All clojure does is agree that iteration over a lazy sequence is a valuable concept. It implements this as an abstract protocol, rather than as a concrete implementation on linked lists.

namibj 7y ago

I might add that breaking the naming away (from traditions) also helps breaking the mindset away (from "that's how we always did it"). This allows for unified abstract views on things normally distinguished from each other by words, syntax, conventions and mind. This allows stuff like pattern matching generic functional code like the mighty monad with it's transformer. Learning functional programming incl. higher kinded types (dependent types and such) isn't easy for someone used to e.g. Java,C,C++,Python,Go, and others I can't judge of the top of my head. If you ask yourself why said functional is beneficial, remember the popularity and typical confusion of the Monad posts/articles. You might not quite understand / "get" it, but they keep coming up and the authors seem intelligent. So you (might) just have a case of the Blub Paradox[0]. You need to understand it to grok it's usefulness/desirability. [0]: http://www.paulgraham.com/avg.html http://www.paulgraham.com/avg.html

lonelappde 7y ago

If you are using first and rest, then you are treating whatever sequence you have as a linked list, so you've already lost the plot.

greggyb 7y ago
You can treat any collection or data structure that implements the sequence protocol as a lazy sequence with (seq collection) But you don't have to. If you choose to, you're not tied to a representation of mutable cons cells. There are good reasons to want to iterate over values in a map or a set, while still wanting the lookup characteristics of those collections, rather than a linked list. This is hardly a controversial stance. Python, for example, supports iteration over many of its data structures and it is recommended to implement the dunder methods for iteration on any class that might reasonably be the basis of an iteration. All clojure does is agree that iteration over a lazy sequence is a valuable concept. It implements this as an abstract protocol, rather than as a concrete implementation on linked lists.