es6/env.js

   1 export function new_env(outer={}, binds=[], exprs=[]) {
   2     var e = Object.setPrototypeOf({}, outer)
   3     // Bind symbols in binds to values in exprs
   4     for (var i=0; i<binds.length; i++) {
   5         if (Symbol.keyFor(binds[i]) === "&") {
   6             e[binds[i+1]] = exprs.slice(i) // variable length arguments
   7             break
   8         } else {
   9             e[binds[i]] = exprs[i]
  10         }
  11     }
  12     return e
  13 }
  14 export const env_get = (env, sym) => {
  15     if (sym in env) {
  16         return env[sym]
  17     } else {
  18         throw Error(`'${Symbol.keyFor(sym)}' not found`)
  19     }
  20 }
  21 export const env_set = (env, sym, val) => env[sym] = val