News

Returning multiple values: semantics

This is an announcement of an upcoming feature. Please see the previous post for syntactic aspect of WCPL multiple values support.

Returning multiple values: syntax

This is an announcement of an upcoming feature.

Relaxed declarations

This is an announcement of an upcoming feature.

Conditional compilation

To support a wider set of scenarios where WCPL code is also compiled by a regular C compiler (which is not that hard due to WCPL being basically a subset of C), WCPL supports a limited set of conditional compilation constructs. The goal was to allow the insertion of fragments targeting various C compilers and platforms to be ignored by WCPL compiler on line-by-line basis.

Generic macros, countof()

In addition to variadic macros, WCPL supports the generic construct that is traditionally used in so-called cover macros that expand to calls of different functions based on types of their argument(s). The construct itself does not have to be used in macros, although in practice it rarely appears anywhere else.

Variadic macros, countof()

Although WCPL macros, having a completely different nature from C macros (expression-based vs. token-based), are limited compared to their C counterparts, some of advanced features of C macros are supported in a form that allows for interoperability. One such feature is variadic macros, i.e. macros accepting variable number of arguments.

WCPL macros

WCPL has a simple macro mechanism that mimics most frequent patterns used by C macro writers while being implemented via an entirely different mechanism. While C macros manipulate sequences of tokens, WCPL macros manipulate complete expressions; substitution is done on the level of abstract syntax trees. Although it makes it impossible to use some advanced tricks empoyed by C macro experts, such as introducing unpaired braces, substituting types, and glueing identifiers from individual parts, most popular macro patterns still can be employed, and made to behave in the same way between WCPL and C.

Functions with variable arguments, countof()

WCPL fully supports <stdarg.h> header defining a type and three macros for advancing through an array of values supplied as the value of the ... (ellipsis) argument. Internally, this argument comes last in the argument list and has the va_list type, defined internally as follows:

New packaging of bundled libraries

Starting with version 1.04, all bundled libraries (see lib folder) are embedded inside the executable, so using them needs no -L/-I options. All embedded library files are logged as belonging to res:// pseudo-directory (a compressed archive inside l.c); res://lib/ is always used as a fallback search location, so explicit locations given via -L have priority and can override built-in versions if needed.

The embedded archive is generated with the help of baz archiver (see https://github.com/false-schemers/baz); the command is:

baz cvfz l.c --exclude="src" --exclude="lib/include/NDEBUG" --exclude="README.md" --zopfli=1000 wcpl/lib

It uses external zopfli* compressor to get excellent compression rates for .wo files, so the whole built-in archive adds only about 90K to size of the executable.

* [zopfli]: https://github.com/google/zopfli

Welcome to WCPL

This is a test. I will be posting some notes on WCPL design here.