Partial application of a function. Use this to prepare a function with arguments for testing.

See:

• https://en.wikipedia.org/wiki/Currying
• https://en.wikipedia.org/wiki/Partial_application

Example:

// A function with 2 arguments:
const result = await fn(arg1, arg2)
const check = result => ok(result > 0)
check(result)

// Is tested like this:
expect("description",
  curry(fn, arg1, arg2),
  check)