Lisp-stick on a Python

Post by jahewson » Tue, Nov 15, 2022, 6:24 AM UTC

jlarocco wrote: post #59

p-e-w wrote: post #52

I've been hearing claims my entire programming career about how Lisp is supposedly "superior" to mainstream programming languages, but I've never seen a concise code example that actually demonstrates this. For instance, it's easy to demonstrate how Rust is superior to C: Just show a short piece of code where an array is returned from a function. In C, this will involve raw pointers and manual memory management with…

Considering Lisp was here first, shouldn't the real question be "why use Rust/C++/Python when there's Lisp?" You can't even create a real closure in Rust. I'd love to see 10 lines of Rust that showed me something that: 1. I can't easily do in Lisp. 2. Actually matters in practice.

Post by Jtsummers » Tue, Nov 15, 2022, 6:36 AM UTC

crdrost wrote: post #67

p-e-w wrote: post #52

I've been hearing claims my entire programming career about how Lisp is supposedly "superior" to mainstream programming languages, but I've never seen a concise code example that actually demonstrates this. For instance, it's easy to demonstrate how Rust is superior to C: Just show a short piece of code where an array is returned from a function. In C, this will involve raw pointers and manual memory management with…

I mean the famous example is of course, (define (eval exp env) (cond ((number? exp) exp) ((string? exp) exp) ((symbol? exp) (lookup exp env) ((eq? (car exp) 'quote) (cadr exp)) ((eq? (car exp) 'lambda) (list 'closure (cdr exp) env)) ((eq? (car exp) 'cond) (eval-cond (cdr exp)) (else (apply (eval (car exp) env) (eval-list (cdr exp) env))))) which uses a Lisp to define itself. This means roughly that if you understand…

Post by hamandcheese » Tue, Nov 15, 2022, 6:52 AM UTC

crdrost wrote: post #67

p-e-w wrote: post #52

I've been hearing claims my entire programming career about how Lisp is supposedly "superior" to mainstream programming languages, but I've never seen a concise code example that actually demonstrates this. For instance, it's easy to demonstrate how Rust is superior to C: Just show a short piece of code where an array is returned from a function. In C, this will involve raw pointers and manual memory management with…

I mean the famous example is of course, (define (eval exp env) (cond ((number? exp) exp) ((string? exp) exp) ((symbol? exp) (lookup exp env) ((eq? (car exp) 'quote) (cadr exp)) ((eq? (car exp) 'lambda) (list 'closure (cdr exp) env)) ((eq? (car exp) 'cond) (eval-cond (cdr exp)) (else (apply (eval (car exp) env) (eval-list (cdr exp) env))))) which uses a Lisp to define itself. This means roughly that if you understand…

Post by japanuspus » Tue, Nov 15, 2022, 6:54 AM UTC

jahewson wrote: post #72

jlarocco wrote: post #59

Earlier quoted context omitted.

Considering Lisp was here first, shouldn't the real question be "why use Rust/C++/Python when there's Lisp?" You can't even create a real closure in Rust. I'd love to see 10 lines of Rust that showed me something that: 1. I can't easily do in Lisp. 2. Actually matters in practice.

This a trick question because 10 line programs are trivial. Please show me a high performance hardware-accelerated 3D game engine written in lisp. Or a web browser.

Post by Jtsummers » Tue, Nov 15, 2022, 7:04 AM UTC

hamandcheese wrote: post #76

crdrost wrote: post #67

Earlier quoted context omitted.

I mean the famous example is of course, (define (eval exp env) (cond ((number? exp) exp) ((string? exp) exp) ((symbol? exp) (lookup exp env) ((eq? (car exp) 'quote) (cadr exp)) ((eq? (car exp) 'lambda) (list 'closure (cdr exp) env)) ((eq? (car exp) 'cond) (eval-cond (cdr exp)) (else (apply (eval (car exp) env) (eval-list (cdr exp) env))))) which uses a Lisp to define itself. This means roughly that if you understand…

> This means roughly that if you understand enough Lisp to understand this program Any recommendations on good resources for learning Lisp to a degree that this program is understandable?

  def eval(x, env=global_env):
      "Evaluate an expression in an environment."
      if isinstance(x, Symbol):    # variable reference
          return env.find(x)[x]
      elif not isinstance(x, List):# constant 
          return x   
      op, *args = x       
      if op == 'quote':            # quotation
          return args[0]
      elif op == 'if':             # conditional
          (test, conseq, alt) = args
          exp = (conseq if eval(test, env) else alt)
          return eval(exp, env)
      elif op == 'define':         # definition
          (symbol, exp) = args
          env[symbol] = eval(exp, env)
      elif op == 'set!':           # assignment
          (symbol, exp) = args
          env.find(symbol)[symbol] = eval(exp, env)
      elif op == 'lambda':         # procedure
          (parms, body) = args
          return Procedure(parms, body, env)
      else:                        # procedure call
          proc = eval(op, env)
          vals = [eval(arg, env) for arg in args]
          return proc(*vals)