This module contains what might be described as faux lenses. This includes support for composition, getting, setting, etc.

Specifies how the record should be traversed when a diff is computed.

leaf ~field ~equal is a terminal node in the spec tree.

When computing a diff, the fields are gotten using Field.get and compared with equal. If the values are not equal, the diff includes the new value.

child ~field ~spec is an intermediate node in the spec tree.

When computing a diff, the diff for the children is recursively computed.

opt_child ~field ~spec is an optional intermediate node in the spec tree.

When computing a diff, the diff for the children is recursively computed if the child is present.

many specs combines specs into a single spec

Represents a difference between two records of the same type.

compute v0 v1 spec returns a list of all the differences between v0 and v1 using spec to traverse the values.

apply v diff returns v with diff applied

apply_all v diffs returns v with all diffs applied