text: const regl = require('regl')({extensions: ['OES_texture_float']});
  const gpgpu = require('../')(regl);
  const iota = require('iota-array');
  const show = require('ndarray-show');
  
  const shape = [2, 2, 4];
  const n = shape.reduce((a, b) => a * b);
  
  const a = 2.0;
  const x = gpgpu.array(iota(n), shape);
  const y = gpgpu.array(iota(n), shape);
  const z = gpgpu.array(null, shape);
  
  const op = gpgpu.map({
    args: ['scalar', 'array', 'array'],
    body: `vec4 compute (float a, vec4 x, vec4 y) {
      return a * x + y;
    }`
  });
  
  op(z, a, x, y);
  
  console.log('x =\n' + show(x.read()));
  console.log('y =\n' + show(y.read()));
  console.log(a + ' * x + y =\n' + show(z.read()));
  