Egison Pattern Source
The egison-pattern-src provides a standalone syntax definition for patterns in Egison programming language. This package enables you to embed Egison's patterns in your parser (pretty-printer) by supplying expression and name parsers (printers) externally. For the uses in Haskell source code, such adaptors for haskell-src-exts and template-haskell are also available here as egison-pattern-src-haskell-mode and egison-pattern-src-th-mode respectively.
Syntax
The following is a simplified syntax of pattern expressions where x
, v
, op
and e
are respectively names, variable names, user-defined infix operators and expressions in host language.
p ::= _ (wildcard pattern)
| $v (pattern variable)
| #e (value pattern)
| ?e (predicate pattern)
| p & p (and pattern)
| p | p (or pattern)
| !p (not pattern)
| p op p (user-defined infix pattern)
| x (constructor pattern without argument)
| (x p_1 p_2 ... p_n) (constructor pattern with arguments)
Development
To build and test egison-pattern-src
locally, run:
$ make test # or just `cabal new-test all`
You can use make watch
to watch for file changes and re-run tests.
License
egison-pattern-src is distributed as open source software under the terms of the 3 clause BSD License. See LICENSE for details.