forked from GitHub/gf-core
4c0c7a994b
The output from commands is represented as ([Expr],String), where the [Expr] is used when data is piped between commands and the String is used for the final output. The String can represent the same list of trees as the [Expr] and/or contain diagnostic information. Sometimes the data that is piped between commands is not a list of trees, but e.g. a string or a list of strings. In those cases, functions like fromStrings and toStrings are used to encode the data as a [Expr]. This patch introduces a newtype for CommandOutput and collects the functions dealing with command output in one place to make it clearer what is going on. It also makes it easier to change to a more direct representation of piped data, and make pipes more "type safe", if desired.