stew / left-cats Goto Github PK

What are the laws for a valid LeftPad instance?

One law comes to mind: (l <= length a) → leftPad(a)(l, p) == a. This is troublesome to encode, because in general F doesn't have any constraints that provide a generic length. A less powerful special case of this law that doesn't require length is l == 0 in which we get the identity leftPad(a)(0, p) == a.

Your string-padding algorithm is linear, which is not faithful to the quadratic algorithm used in the Javascript reference implementation.

A library of this sophistication needs proper support. I suggest at least a Gitter channel.

Simulacrum dependency, and the relative import, should be removed since it's not used.