Data::Sah::Coerce contains a standard set of coercion rules for Data::Sah. It is
separated from the Data-Sah distribution and can be used independently.

A coercion rule is put in
Data::Sah::Coerce::$COMPILER::To_$TARGET_TYPE::From_$SOURCE_TYPE::DESCRIPTION
module, for example: Data::Sah::Coerce::perl::To_date::From_float::epoch for
converting date from integer (Unix epoch) or
Data::Sah::Coerce::perl::To_date::From_str::iso8601 for converting date from
ISO8601 strings like "2016-05-15".

Basically, a coercion rule will provide an expression (expr_match) that
evaluates to true when data can be coerced, and an expression (expr_coerce) to
actually coerce/convert data to the target type. This rule can be combined with
other rules to form the final coercion code.