es6 template strings for APL

apl-template-strings.js

// es6 template strings for APL
// npm install apl

"use strict"

// from: https://github.com/ngn/apl/blob/master/examples/1-mult.apl
// note: http://s.mlkshk-cdn.com/r/97VP

apl`
  ⍝ Multiplication table
  ⍝  a × b    scalar multiplication, "a times b"
  ⍝  ∘.       is the "outer product" operator
  ⍝  A ∘.× B  every item in A times every item in B
  ⎕ ← (⍳ 10) ∘.× ⍳ 10
`
// prints:
// 0 0  0  0  0  0  0  0  0  0
// 0 1  2  3  4  5  6  7  8  9
// 0 2  4  6  8 10 12 14 16 18
// 0 3  6  9 12 15 18 21 24 27
// 0 4  8 12 16 20 24 28 32 36
// 0 5 10 15 20 25 30 35 40 45
// 0 6 12 18 24 30 36 42 48 54
// 0 7 14 21 28 35 42 49 56 63
// 0 8 16 24 32 40 48 56 64 72
// 0 9 18 27 36 45 54 63 72 81

//------------------------------------------------------------------------------
function apl(lits) {
  let APL  = require("apl")
  let subs = [].slice.call(arguments, 1)

  let source = []

  for (let i=0; i<subs.length; i++) {
    source.push(lits[i])
    source.push(subs[i])
  }

  source.push(lits[lits.length-1])
  source = source.join("")

  let result
  let ePrefix = `error compiling '${JSON.stringify(source)}'`

  try {
    result = APL(source)
  }
  catch (e) {
    throw new Error(`${ePrefix}: error compiling APL: ${e.message}`)
  }

  return result
}