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From: Duncan Mak <duncanmak@gmail.com>
Date: Fri, 3 Jul 2020 17:24:54 -0400
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Subject: Extending functional call syntax for Sequences to include Maps
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Hello,

I've been reading the Kawa docs quite seriously when I was looking to learn
the Pattern design. I noticed that Sequences implement Procedure, as shown
here in the documentation:

To extract an element from Scheme sequence of type stype there is usually a
function stype-ref. For example:
(define vec1 (vector 5 6 7 8))
(vector-ref vec1 2) =E2=87=92 7


More concisely, you can use (Kawa-specific) function call syntax:

(vec1 3) =E2=87=92 8


Which is pretty neat (and reminds me of what they did in Clojure also,
http://clojure-doc.org/articles/language/functions.html#sets-as-functions).

I was a little disappointed when I found out that this doesn't work for
Maps, which is also something Clojure allows [0]:

;; This is Clojure not Scheme

({:age 42 :name "Joe"} :name)     ; =E2=87=92 "Joe"
({:age 42 :name "Joe"} :age)      ; =E2=87=92 42
({:age 42 :name "Joe"} :unknown)  ; =E2=87=92 nil


[0]
http://clojure-doc.org/articles/language/functions.html#maps-as-functions

Duncan.