“Lispiness”

Why Lispers  like Lisp & family {Common Lisp, Clojure, Scheme, etc} ?

The following Clojure “Lispiness”:

  1. “Immutable” Data – protect from modifying data at run-time.
  2. Simple basic structures (list, vector, map, set) are enough
  3. Complex behaviour can be built with just simple functions.
  4. “It is better to have 100 functions operate on 1 data structure than 10 functions on 10 data structures.”
  5. Code = Data
  6. First-class functions: treat function  as argument, or return a function:
    eg. (map inc [0 1 2 3]) => (1 2 3 4).
  7. Pure functions: 1) No side-effect like C/Java/etc; 2) “Referentially Transparent ” ie. always return the same result if given the same arguments.
  8. Powerful meta-programming: Macros
  9. Easy to extend : write a new language or dialect with Lisp.
  10. Structural Sharing: Old data structure and modified data structure shared within a Tri.

    11. image

(John McCarthy 1960): 《Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I》
He defined the entire Lisp language in terms of only
◇ 7 functions (car cdr cond cons eq quote lambda) and
◇ 2 special forms (atom label)