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- Language type:
Modula-3 is a compiled procedural that
supports object-oriented and block-structured
programming. It is a descendant of Modula-2
and Pascal, and is intended for application
development, large-scale software
engineering, and computer science
As a descendant of Pascal, Modula-3 is
strongly typed and can enforce type safety.
The language supports a conventional
set of data types: numbers, enumerations, strings,
records, sets, and arrays. Modula-3 supports the usual control flow
selection and looping constructs.
good support for modular programming, including
subroutines and modules with explicit
Unlike Pascal, Modula-3 has full support
for abstract data types and
dynamic memory management with garbage
collection, generics, exception handling,
and concurrency. It is an
important part of Modula-3's claim to being
industrial-strength that it includes
robust error handling and multi-threading
as part of the language.
Modula-3 does not support some OOP features
that it's designers believed would overcomplicate
the language or detract from productive
software development: multiple
operator overloading, and
Module-3's object-oriented programming model
is very simple: an object is simply a
record type augmented with a method suite.
Superclass method overloading is supported.
Pascal compilers attempt to enforce type
safety in every line of a program. A
Modula-3 compiler allows some modules to
be designated as explicitly unsafe, freeing
the programmer to use tricky or
machine-dependent techniques to gain
efficiency or access to hardware.
There is a fairly wide variety of support
libraries available for Modula-3, including
ones for network communication,
object persistence, database access, 3D rendering,
and graphical user interfaces.
Early implementations of Modula-3 produced
C code for native compilation, but modern
systems produce native machine code directly.
Both commercial and free compilers for
Modula-3 are available, for all major
platforms include Unix, Linux, and WindowsNT.
Digital Equipment Corp, one of the
originators of the language, makes a free
compiler available in source form.
At least one commercial implementation of Modula-3
is available as a comprehensive development
environment. Information about Modula-3 is
also fairly easy to find on the WWW.
Luca Cardelli et al, Olivetti and DEC, 1988.
- See Also:
Developers that have used Modula-3 have
had praise for its elegance and completeness.
It has a large feature set, but not
so large or complex
as to be overwhelming (e.g. Ada).
Facilities that you need for serious
system development are built-in, like
concurrency and garbage collection.
It is something of a mystery that
Modula-3 is not more widely employed (perhaps
its family relationship with Pascal, regarded
by many as too self-limiting for serious
development, scares developers away).
The direct linguistic predecessor of
Modula-3 was Modula-2+, an enhancement of
Modula-2 incorporating ideas from Mesa.
Niklaus Wirth was consulted on the design
of Modula-3, but was not the primary
designer as he was for Modula-2.
At this time, Modula-3 is not the subject
of any formal standardization activities.
- Sample code:
An example of using the Modula-3 VBTKit GUI
MODULE Push EXPORTS Main;
IMPORT Trestle, VBT, TextVBT, RigidVBT, ButtonVBT, BorderedVBT, HVSplit,
action of button when pushed
PROCEDURE QuitAction (self: ButtonVBT.T; READONLY cd: VBT.MouseRec) =
Trestle.Delete(main); (* NB. "main" is visible here. *)
horz = 30.0; (* horizontal size "hello" window *)
vert = 10.0; (* vertical size of "hello" window *)
hello := RigidVBT.FromHV(TextVBT.New("Hello World"), horz, vert);
quit := ButtonVBT.New(ch := TextVBT.New("Quit"), action := QuitAction);
main := HVSplit.Cons(Axis.T.Ver, hello, BorderedVBT.New(quit));
Descriptions in this dictionary are ©1997-99 Neal Ziring. Some
examples copyright of their respective authors. Some
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Dictionary and script maintained by Neal Ziring, last major modifications 3/18/98. Most recent
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