プログラマ向け RPN 電卓

quick RPN calculator for hackers

Pros: functions also can be called without prefixing quotes (‘), and function quote (#’) is no longer required to push raw symbols

Cons: if a name is both defined as function and variable, it’s not possible to refer the variable definition

• Function call examples
  • last version

    random   -> ERROR: void variable "random"
    'random  -> 12345
    #'random -> random
            

  • current version

    random   -> 12345
    'random  -> random
            

• Variable reference examples
  • last version

    default-directory   -> "~/"
    'default-directory  -> void function "default-directory"
    #'default-directory -> default-directory
            

  • current version

    default-directory   -> "~/"
    'default-directory  -> default-diectory
            

rpn-calc is designed to be a handy tool for daily programming use.

• rpn-calc uses popup instead of making a new window, and you don’t need to move your eyes between the edit point and the calculator window
• rpn-calc displays hints like binary representation of numbers, which may be useful for programmers
• rpn-calc is designed to be used with minimal key presses.
• rpn-calc is easy to customize. You can add/remove some operators with just one or two lines of Emacs Lisp
• You can push not only numbers but any Emacs Lisp objects to the stack, and you can apply any Emacs Lisp function to them. So rpn-calc can also be used as an interactive, RPN version of eval-expression

See also “Other Features” section.

Require this script

(require 'rpn-calc)

and invoke with M-x rpn-calc.

1. You can push objects by pressing [SPC] after entering an S-expression (try: 120[SPC]). You can also push more complex expressisons like (buffer-name (current-buffer))[SPC], or quoted expressions

   Pro tip: in Emacs, #xFF = #b11111111 = 255

2. When you enter an operator name, top elements in the stack are popped and applied to the operator (try: 1[SPC]sin). List of built-in operators are listed in the section below. You can add some operators by pushing list like (NAME ARITY . FUNCTION) to rpn-calc-operator-table

   (push '("twice" 1 . (lambda (x) (* x 2))) rpn-calc-operator-table)
       

3. You can also push a function name to call it (try: 10[SPC]number-to-string[SPC]), or a variable name to refer it (try most-positive-fixnum[SPC]). If the function accepts &rest arguments, all elements in the stack are passed (try: 10[SPC]20[SPC]30[SPC]list[SPC]). This behavior can be changed via rpn-calc-apply-rest-args. Note that if a symbol is both defined as function and variable, function definition takes precedence

• math

  +

  pop y, x and push (+ x y)

  –

  pop y, x and push (- x y)

  /

  pop y, x and push (/ x y)

  *

  pop y, x and push (* x y)

  %

  pop y, x and push (mod x y) (modulo)

  sin

  pop x and push (sin x) (sine)

  cos

  pop x and push (cos x) (cosine)

  tan

  pop x and push (tan x) (tangent)

  ln

  pop x and push (log x) (natural log)

  lg

  pop x and push (log x 10) (log base 10)

  log

  pop y, x and push (log y x) (log base x)

• bitwise

  &

  pop y, x and push (logand x y) (bitwise and)

  |

  pop y, x and push (logor x y) (bitwise or)

  ^

  pop y, x and push (logxor x y) (bitwise xor)

  ~

  pop x and push (lognot x) (bitwise not)

  <<

  pop y, x and push (ash x y) (shift left)

  >>

  pop y, x and push (ash x (- y)) (shift right)

• int <-> float

  float

  pop x and push (float x) (int -> float)

  int

  pop x and push (truncate x) (float -> int)

  trunc

  pop x and push (truncate x) (round toward zero)

  floor

  pop x and push (floor x) (largest integer < x)

  ceil

  pop x and push (ceil x) (smallest integer > x)

  round

  pop x and push (round x) (nearest integer to x)

• stack manipulation

  <Backspace>

  pop an item

  :

  pop x, and push x twice (duplicate)

  \

  pop x, y and push y, x (swap)

• Implicit “SPC”

  rpn-calc automatically pushes the input (without pressing “SPC”) to reduce keypresses, when :

  non-digit character is entered after a number

  Example: 1evenp[SPC] is equivalent to 1[SPC]evenp[SPC].

  outer-most closing paren is entered

  Example: (1+ (point)) is equivalent to (1+ (point))[SPC].

  build-in operator name is completed

  Example: 1sin is equivalent to 1[SPC]sin[SPC].

• Display hints for inserted objects
  • hex/binary representation of integers
  • IEEE754 representation of floating-point numbers
  • arglist of functions
  • variable value of symbols
• Push buffer string to the stack

  You can push expressions in a buffer to the stack by selecting the expression before invoking rpn-calc

• Insert result to the buffer

  You can insert the result by pressing RET in rpn-calc

• Push items into middle of the stack.

  You can move cursor with rpn-calc-next (bound to C-n by default) and rpn-calc-previous (C-p resp.) while in rpn-calc, to insert items into middle of the stack (try: 1[SPC]2[SPC]3[C-n][SPC])

• popup.el