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2 points by akkartik 1694 days ago | link | parent

Interesting! Clearly my knowledge of the clojure primitives was extremely vague; I wasn't even aware that they operated on forms rather than function values.

Arc could eliminate the ->/->> dichotomy in another way entirely, using the existing syntax for single-arg fns. The examples at would become (arc-ish pseudocode):

  (-> (range) [map [* _ _] _] [filter even? _] [take 10 _] [reduce + _])
  (-> 5 [+ _ 3] [/ 2 _] [- 1 _])
At the same time, the examples at become:

  (-> "a b c d" upcase [replace _ "A" "X"] [split _ " "] first)
What's more, you could mix first and last because all the arguments are actual values rather than hacky s-exprs. I already used that in the second example above, if you look closely.


The one missing use case is this:

  (-> animals 'dog 'thaddeus 'age)
Arc just has a different, retro-email solution for that:

Though it all unravels if one of the keys is a string. Ok, we could use some help here. But it feels like a separate mechanism; I would avoid mixing `(,form ,x) and `(,x ,form) in different paths of a single macro.


Hmm, even this isn't too bad:

  (-> animals [_ 'dog] [_ 'thaddeus] [_ 'age])
You don't save typing compared to:

  (((animals 'dog) 'thaddeus) 'age)
But the matching parens are closer together and so easier to read.

2 points by thaddeus 1694 days ago | link

I agree, mixing `(,form ,x) and `(,x ,form) is really ugly and I do like

much better - I forgot arc could do that lol.

Also, if anyone were really caught up on the strings as keys hiccup, the idiomatic approach for arc would likely be this: If one could only find a pleasant & available symbol.