Multiparadigm

Concepts and Architecture of Vista: A Multiparadigm Programming Environment
Visual multiparadigm programming: visual + object-oriented (signal flow + data flow); from Proceedings of 10th IEEE/CS Symposium on Visual Languages, St. Louis, USA, 4-7 October 1994. Downloads: HTML, PS.
http://www.swe.uni-linz.ac.at/publications/abstract/TR-SE-94.17.html

ELAN
Created 1974 by Technical University of Berlin group, as alternative to BASIC in teaching, for systematic programming, and related styles: top-down, bottom-up, recursive, modular, syntax-directed. Descriptions, brief resource list, documents. English, Deutsch.
http://os.inf.tu-dresden.de/L4/l3elan.html

Heron
Home site. Has brief description, specification, tutorial, related articles, download.
http://www.heron-language.com/

Heron-Centric: Ruminations of a Language Designer
Weblog on language design issues, software development techniques, news, on Heron language, and similar languages like Java, C++.
http://www.artima.com/weblogs/index.jsp?blogger=cdiggins

Kx Systems, Inc.
Makes K, advanced vector oriented, functional language, one of the fastest application development environments (according to Bell Laboratories Benchmarking), and allows very fast processing of large datasets.
http://www.kx.com/

Lfyre
General purpose, compiled; high performance, expressiveness, flexibility. Many features found in other languages, and extra features: creating new operators, keywords, programming paradigms. News, download. [SourceForge]
http://sourceforge.net/projects/lfyre/

Lightweight Languages as Software Engineering Tools
Usenix Paper discussing multiparadigm programming as part of a larger topic.
http://www.usenix.org/publications/library/proceedings/dsl97/full_papers/spinellis/spinellis_html/spinellis.html

Lucid
Functional dataflow language, invented by Bill Wadge, Ed Ashcroft. Variables and expressions denote streams-sequences of data items. Input and output are streams, so a program is a Unix-style filter. Was basis for French real-time/reactive languages Lustre, Signal.
http://i.csc.uvic.ca/home/hei/ihei.cgi?context=%3Ctop:%3C%22lucid%22%3E%3E

Multiparadigm Programming Group
At Leibniz Laboratory, Grenoble, France; research topics, news, publications, members. In English and Français.
http://www-leibniz.imag.fr/PMP/

Multiparadigm Programming Language
Brief description, language list sorted by count and supported paradigms. [Wikipedia]
http://en.wikipedia.org/wiki/Multi-paradigm_programming_language

Needle
Pure object-oriented, functional language, statically typed, garbage collected; mixes ideas from Dylan, Lisp, Scheme; ML; Cecil, Smalltalk; description, slide show, downloads, links. [Open Source, MIT]
http://www.nongnu.org/needle/

Nial Systems Ltd.
NIAL, Nested Interactive Array Language, mixes aspects of functional array and procedural languages. Rich primitives set makes it easy, fast to code loop-free data-driven algorithms. Also Q'Nial IDE, and Nial Data Engine embeddable interpreter. [Open Source, Artistic Licence]
http://www.nial.com/

An Object Model for Multiparadigm Programming
Presented at OOPSLA 1994.
http://www.spinellis.gr/pubs/conf/1994-OOPSLA-Multipar/html/mlom.html

Piccola: A Small Composition Language
PI based COmposition LAnguage: research language to explore the paradigm: Application = Components + Scripts. From the University of Berne.
http://www.iam.unibe.ch/~scg/Research/Piccola/

ResearchIndex: From Competition to Amalgamation of Different Programming Paradigms
Describes basic elements (data, actions, tunings, voids, mixtures, ...) and principles of programming (stratification, implicit knowledge, limited freedom, ...), directed to amalgamating different programming paradigms (imperative, object-oriented, functional, constraint, ...) in a unified process of generating computer system models.
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.32.9545

Scala
General purpose language; multiparadigm (object-oriented, functional, concurrent elements); statically typed, type-safe; focus: Web services. Successor of Funnel. Interoperates with Java VM or .NET, XML aware. [Open source, BSD-like license]
http://www.scala-lang.org/

UFO: United Functions and Objects: Draft Language Description
Download of UMCS-92-4-3.
http://intranet.cs.man.ac.uk/Intranet_subweb/library/cstechrep/Abstracts/UMCS-92-4-3.html

X Language: xlang
The eXtensible Language: easy to use, multi-syntax, portable set of APIs to create CLI and GUI applications for Unix/X11 and Win32; will ease making big applications, has interpreter/compiler/debugger. [Open Source, GPL]
http://www.nongnu.org/xlang/

XLR: Extensible Language and Runtime
XL is designed to implement the ideas of Concept Programming. It can apply to many domains and problem spaces, not only a small subset of the problems users must solve.
http://xlr.sourceforge.net/

Heron: Introducing The Heron Programming Language
Forum with many comments. [Slashdot] <small>(December 8, 2004)</small>
http://developers.slashdot.org/article.pl?sid=04/12/08/1944233