Compiles the pipeline.

Each pipeline element should be a tuple of {validator_name, options, guards}

This function expects a reversed pipeline, i.e. the last validator to be called comes first in the list.

This function returns a tuple where the first element is a quoted reference to the changeset being validated, and the second element being the compiled quoted pipeline.

example

Example

Strukt.Validator.Builder.compile(env [
  {Strukt.Validators.RequireOnInsert, [:field], quote(do: changeset.action == :insert),
  {Strukt.Validators.RequireOnUpdate, [:other_field], quote(do: changeset.action == :update)},
  {Strukt.Validators.RequireOnChange, [:other_field], true},
], [])