Haskell implementation of 4-value parser combinators.Based on the classic paper:

Andrew Partridge, David Wright: Predictive parser combinators need four values to report errors. Journal of Functional Programming 6(2): 355-364, 1996

This repo contain a Haskell implementation of combinators, coded in both the 4-way variant style, and also the 4-continuation style. And an example of the use of the combinators to encode a parser for a small expression language.

• par4v.hs -- combinators in 4-way variant style
• par4c.hs -- combinators in 4-continuation style
• ast.hs -- AST for small expression language
• syntax.hs -- parser for the expression language using the combinators (can use either combinator style)
• tests.hs -- unit tests for parser (success and failure)
• main.hs -- run the unit tests

Build/run:

• $ ghc -Wall -fno-warn-name-shadowing --make result par4v par4c ast syntax tests main -o main.exe
• $ main.exe