> Any competent Clojure programmer would likely have known most of the Clojure core functions by heart

I really like Clojure, but I've always found the relatively huge set of core functions to be a major barrier to entry. I always have this nagging feeling of "there's probably a core function I'm missing to make doing this or that easier", and end up spending a lot of time poring over documentation instead of just programming. Maybe that's just how it is, and the answer is to push through it until you know the functions better, but there's something to be said for shipping a language with fewer, simpler, more primitive operations.

It's definitely a taste thing. I found going from the batteries-included Python to the very limited strict C89 ansi-pedantic-standard rather annoying, but at the same time I got a lot of pleasure building a game from scratch in SDL instead of using a full-fledged engine that would have replaced a lot of my code with one-liners or even automagically managed bits in the background. I think a more overkill approach is better economically than being conservative, and in Lisp especially including a ton of common macros like 'or out of the box saves every other programmer from writing their own. I could go the rest of my life without seeing yet another custom <insert data structure here> in C or C++ which has a good implementation natively in almost every other language. I wish JavaScript had more builtin as I'm often in the position that things I take for granted as being there in Python, Java, or Clojure require me to roll my own in JS and that can easily take hundreds of lines of my own code or dependencies depending on what it is. (e.g. anything involving large integers.) I'm greatly thankful for regex support in my daily languages. I remember in a high school programming contest, one guy didn't know Java had regexes (or even what regexes were) while I knew them from using them in PHP to validate form inputs... Needless to say, he never got a fully working parser in the time he had for the problem.

You may find https://github.com/jonase/kibit helpful for some things. Otherwise I'd recommend just dedicating time to exploring the builtins so that you can resist the urge to wander while you should be programming -- there was a very interesting series a few years back some blogger made that covered all of Python's builtin modules, doing it yourself (or maybe there's one now for Clojure) is worthwhile. I also like to visit things like http://www.clojure-toolbox.com/ from time to time to see if there's anything new and exciting in areas of my interest.

From a cognitive point of view, learning a large number of idioms is more manageable for human beings than having to reinvent the mental constructs from primitives every time. This human capacity of dealing with idioms is what called "chunking" in psychology (https://en.wikipedia.org/wiki/Chunking_%28psychology%29)

Human has unlimited memory capacity and fast memory access, whereas human logical processing power is fairly limited and error prone. That's why any real human language has a large vocabulary.

I would prefer if there were very few un-namespaced functions which are limited to those I'm likely to use on any given line of code, and an intuitive namespace hierarchy for everything else. Basically, I think the core functions should be similar to reserved syntax is in other languages: a limited set of things that form the structure of most code, with more specific stuff imported from elsewhere. Note I'm not saying that the clojure way is "wrong", just that this[0] is a daunting set of information to be expected to "know by heart".

[0]: https://clojure.github.io/clojure/clojure.core-api.html

Ah, I see. I can't disagree with that :)