Function positify

app/core/utils.js:710–710

const round = _.curry((digits, n) => n = +n.toFixed(digits))

const positify = func => params => function (x) { if (x > 0) { return func(params)(x) } else { return 0 } }

// f(x) = ax + b
const createLinearFunc = params => x => ((params.a || 1) * x) + (params.b || 0)