Module CPP.DefaultRules

Default Rules Preprocessor

This module contains the implementation of a preprocessor for Curry programs in order to implement default rules and deterministic operations.

A default rule for a function f processed by this preprocessor must be defined as a rule defining the operation f'default, e.g., 

nlookup key (_ ++ [(key,value)] ++ _) = Just value
nlookup'default _   _                 = Nothing

The concept of default rules and their implementation are described in 

Sergio Antoy, Michael Hanus: Default Rules for Curry
Theory and Practice of Logic Programming,
Vol. 17, No. 2, pp. 121-147, 2017

An operation can be marked as deterministic by decorating the result type with DET, e.g., 

psort :: [Int] -> DET [Int]

The concept of deterministic operations and their implementation are described in 

Sergio Antoy, Michael Hanus:
Eliminating Irrelevant Non-determinism in Functional Logic Programs
Proc. 19th Int. Symp. on Practical Aspects of Declarative Languages,
Springer LNCS 10137, pp. 1-18, 2017

This preprocessor can be invoked by the Curry preprocessor currypp with the option defaultrules (provided as a FRONTEND option, see the example programs in the directory examples/DefaultRules).

Author: Michael Hanus

Version: November 2021

Summary of exported operations:

translateDefaultRulesAndDetOps :: Int -> [String] -> String -> CurryProg -> IO (Maybe CurryProg)  Deterministic 
Start default rules/deterministic operations transformation in "preprocessor mode".

Exported operations:

translateDefaultRulesAndDetOps :: Int -> [String] -> String -> CurryProg -> IO (Maybe CurryProg)  Deterministic 

Start default rules/deterministic operations transformation in "preprocessor mode". It is assumed that the Curry program passed as the last argument was read with readUntypedCurry which is important to process DET annotations!