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As someone who has learnt and loves Lisp it's really confusing to me that REPL has come to mean simply command interface. This is the REPL: (loop (print (e

As someone who has learnt and loves Lisp it's really confusing to me that REPL has come to mean simply command interface. This is the REPL: (loop (print (eval (read))))

nixpulvis 8y ago
The key for me is that a REPL reads, then evaluates (generally involving printing), then starts over (looping). Bash for example fits this criteria. I'm as much of a fan of lisp as anyone, but it doesn't need to be literally printing the result of `eval` to be a REPL in my eyes.
- lispm 8y ago
  bash doesn't print the result of an evaluation, the commands print if the want it's more a PEL: Parse Execute Loop
  - earenndil 8y ago
    In that case, most lisp 'repls' don't satisfy your definition either.
    - lispm 8y ago
      Most Lisp REPLS print a result somewhere.
    - cup-of-tea 8y ago
      The P stands for print. A REPL prints by definition.
      - earenndil 8y ago
        Then what is this? (defun add (a b) (+ a b))
        kbp 8y ago
        That's some Lisp code; if you enter it at a REPL, it prints the result of evaluating it: CL-USER> (defun add (a b) (+ a b)) ADD
        lispm 8y ago
        This is Lisp code defining a function ADD. If you enter it at a Lisp REPL, the REPL will read the expression, evaluate it and store it as a function. The result value is the name of the defined function. The REPL will then print the result, here the name of the function: ADD. CL-USER 13 > (defun add (a b) (+ a b)) ADD As you can see, the function does not print the Lisp symbol 'ADD', it's printed by the REPL. That's the P-component of R E P L, REPL. P stands for PRINT. This means that the REPL will always print a result - unless a Lisp function does not have a result - which is rare. If we execute the function, the REPL prints the result of the function: CL-USER 14 > (add 17 25) 42 Here the result is the number 42.
        kazinator 8y ago
        That is an expression which evaluates to the symbol add. It also has an important side-effect of defining a function.
hinkley 8y ago
Or for those who read left to right: Read Eval Print Loop

As someone who has learnt and loves Lisp it's really confusing to me that REPL has come to mean simply command interface. This is the REPL: (loop (print (eval (read))))

nixpulvis 8y ago

The key for me is that a REPL reads, then evaluates (generally involving printing), then starts over (looping). Bash for example fits this criteria. I'm as much of a fan of lisp as anyone, but it doesn't need to be literally printing the result of `eval` to be a REPL in my eyes.

lispm 8y ago
bash doesn't print the result of an evaluation, the commands print if the want it's more a PEL: Parse Execute Loop
- earenndil 8y ago
  In that case, most lisp 'repls' don't satisfy your definition either.
  - lispm 8y ago
    Most Lisp REPLS print a result somewhere.
  - cup-of-tea 8y ago
    The P stands for print. A REPL prints by definition.
    - earenndil 8y ago
      Then what is this? (defun add (a b) (+ a b))
      - kbp 8y ago
        That's some Lisp code; if you enter it at a REPL, it prints the result of evaluating it: CL-USER> (defun add (a b) (+ a b)) ADD
      - lispm 8y ago
        This is Lisp code defining a function ADD. If you enter it at a Lisp REPL, the REPL will read the expression, evaluate it and store it as a function. The result value is the name of the defined function. The REPL will then print the result, here the name of the function: ADD. CL-USER 13 > (defun add (a b) (+ a b)) ADD As you can see, the function does not print the Lisp symbol 'ADD', it's printed by the REPL. That's the P-component of R E P L, REPL. P stands for PRINT. This means that the REPL will always print a result - unless a Lisp function does not have a result - which is rare. If we execute the function, the REPL prints the result of the function: CL-USER 14 > (add 17 25) 42 Here the result is the number 42.
      - kazinator 8y ago
        That is an expression which evaluates to the symbol add. It also has an important side-effect of defining a function.

hinkley 8y ago

Or for those who read left to right: Read Eval Print Loop