mirror of
https://github.com/peklaiho/madlisp.git
synced 2024-11-26 15:14:12 +00:00
56 lines
1.8 KiB
Plaintext
56 lines
1.8 KiB
Plaintext
|
|
;;
|
|
;; Simple command line calculator which demonstrates the following concepts:
|
|
;; - command parser with arguments
|
|
;; - readline support with history
|
|
;; - main loop
|
|
;;
|
|
;; This is a barebones example for creating interactive command line scripts.
|
|
;; This script should be executed directly, not inside the repl.
|
|
;;
|
|
|
|
;; Define commands
|
|
(def cmdAdd (fn (args) (apply + args)))
|
|
(def cmdDiv (fn (args) (apply / args)))
|
|
(def cmdMul (fn (args) (apply * args)))
|
|
(def cmdSub (fn (args) (apply - args)))
|
|
(def cmdHelp (fn (args) (str "Available commands: " (apply join ", " (keys cmdMap)))))
|
|
|
|
;; And we define a hash-map for command lookups with minimum number of arguments
|
|
(def cmdMap {
|
|
"add": [cmdAdd 2]
|
|
"div": [cmdDiv 2]
|
|
"mul": [cmdMul 2]
|
|
"sub": [cmdSub 2]
|
|
"help": [cmdHelp 0]
|
|
})
|
|
|
|
;; Find the first command which starts with the given name, or null
|
|
(def findCmd (fn (name)
|
|
(if (empty? name) null
|
|
(let (matches (filterh (fn (v k) (prefix? k name)) cmdMap))
|
|
(if (empty? matches) null
|
|
(get matches (first (keys matches))))))))
|
|
|
|
;; Split input by spaces, find command that matches the first word
|
|
;; and call it, giving the rest of the words as arguments.
|
|
(def parseInput (fn (inp)
|
|
(let (words (split " " inp) cname (first words) args (tail words) cmd (findCmd cname))
|
|
(if (null? cmd) (print "Unknown command, try 'help'.")
|
|
(if (< (len args) (second cmd)) (print (str "Give at least 2 arguments to " cname "."))
|
|
((first cmd) args))))))
|
|
|
|
;; Define a file for readline and load it
|
|
(def readlineFile (str HOME "calc_history"))
|
|
(readline-load readlineFile)
|
|
|
|
;; Main loop: Read input from user, add it to readline, and parse it
|
|
(def mainLoop (fn () (let (inp (readline "> "))
|
|
(do (readline-add inp)
|
|
(readline-save readlineFile)
|
|
(print (str (parseInput inp) EOL))
|
|
true))))
|
|
|
|
;; Run it
|
|
(loop mainLoop)
|