const AST = require('./ast')
const OsloError = require('./osloError')

module.exports = {
  '+': (a, b) => new AST.Number({ value: a.value + b.value }),
  '-': (a, b) => new AST.Number({ value: a.value - b.value }),
  '*': (a, b) => new AST.Number({ value: a.value * b.value }),
  '/': (a, b) => new AST.Number({ value: a.value / b.value }),
  '=': (a, b) => new AST.Boolean({ value: a.value === b.value }),
  '>': (a, b) => new AST.Boolean({ value: a.value > b.value }),
  '<': (a, b) => new AST.Boolean({ value: a.value < b.value }),
  '>=': (a, b) => new AST.Boolean({ value: a.value >= b.value }),
  '<=': (a, b) => new AST.Boolean({ value: a.value <= b.value }),
  list: (...args) => {
    return new AST.List({ elements: args })
  },
  length: xs => new AST.Number({ value: xs.elements.length }),
  cons: (x, xs) => new AST.List({ elements: [x, ...xs.elements] }),
  head: xs => xs.elements[0],
  tail: xs => new AST.List({ elements: xs.elements.slice(1) }),
}