Rascal is a programming language; such that meta programs can be created by, understood by, and debugged by programmers.
Rascal primitives include immutable data, context-free grammars and algebraic data-types, relations, relational calculus operators, advanced patterns matching, generic type-safe traversal, comprehensions, concrete syntax for objects, lexically scoped backtracking, and string templates for code generation. It has libraries for integrating language front-ends, for reusing analysis algorithms, for getting typed meta-data out of version management systems, for interactive visualization, etc.
Website | UseTheSource Project | Paper (PDF)
From the website:
One of the goals of Rascal is to allow the definition of Domain-Specific Languages. ... A grammar in Rascal:
module Syntax
extend lang::std::Layout;
extend lang::std::Id;
start syntax Machine = machine: State+ states;
syntax State = @Foldable state: "state" Id name Trans* out;
syntax Trans = trans: Id event ":" Id to;
A fact extractor and checker in Rascal, using concrete syntax:
module Analyze
import Syntax;
set[Id] unreachable(Machine m) {
r = { <q1,q2> | (State)`state <Id q1> <Trans* ts>` <- m.states,
(Trans)`<Id _>: <Id q2>` <- ts }+;
qs = [ q.name | /State q := m ];
return { q | q <- qs, q notin r[qs[0]] };
}
A code generator:
module Compile
import Syntax;
str compile(Machine m) =
"while (true) {
' event = input.next();
' switch (current) {
' <for (q <- m.states) {>
' case \"<q.name>\":
' <for (t <- q.out) {>
' if (event.equals(\"<t.event>\"))
' current = \"<t.to>\";
' <}>
' break;
' <}>
' }
'}"
https://github.com/usethesource/rascal
Rascal Metaprogramming Language. Rascal is a programming language; such that meta programs can be created by, understood by, and debugged by programmers. Rascal primitives include immutable data, context-free grammars and algebraic data-types, relations, relational calculus operators, advanced patterns matching, generic type-safe traversal, comprehensions, concrete syntax for objects, lexically scoped backtracking, and string templates for code generation. It has libraries for integrating language front-ends, for reusing analysis algorithms, for getting typed meta-data out of version management systems, for interactive visualization, etc.
Last modified 07 October 2024