Standard Library

The cRexx standard library is built from a mix of Level B source, rxas, and native support. The release model is explicit: source imports name the namespace to use, and runtime images or linked artifacts provide the bytecode and native pieces needed by the VM.

Core Level B Library: `rxfnsb`

rxfnsb is the Level B built-in-function library. It contains many REXX-familiar functions such as string, numeric, date/time, argument, and conversion helpers. It also contains the supported Level B array helper surface: arrayinsert, arraydelete, arrayappend, arrayprepend, arraypop, arrayshift, arrayget, arrayset, arraycontains, arrayindexof, arrayreverse, arrayjoin, and the older copy, move, sort, format, dump, find, high-water, and drop helpers. New code should prefer these standard BIFs over the deprecated native arrays plugin.

rxfnsb also exposes the .stem class for classic Rexx compound-variable style string-to-string keyed data. Stems support dotted tails and bracket keys, for example s.name and s["customer.id"].

Use it explicitly in reusable Level B source:

options levelb
import rxfnsb

say date("w")
say length("hello")

The crexx driver imports rxfnsb automatically only for headerless top-level scripts.

Many rxfnsb functions are written in cRexx itself under lib/rxfnsb/rexx/. Low-level functionality is provided through RXAS or native runtime support where needed. The mutating array helpers use VM array attribute instructions for insert, delete, shrink, and clear operations, so common list-like operations can adjust the pointer array without a Rexx-level per-element copy loop.

Testing and Debugging Rexx BIFs

The library build is a bootstrap build, not an ordinary application build. Most Rexx BIF source files in lib/rxfnsb/rexx/ are compiled with compiler exits disabled (rxc -x). That means certified-exit statements such as TRACE, PARSE, and ADDRESS are rejected in those files during the BIF build with #CERTIFIED_EXIT_DISABLED.

Do not add TRACE RESULTS directly to a BIF source file to debug it. Use one of these routes instead:

Write or extend a functional test under lib/rxfnsb/tests_functional/ that calls the BIF from normal Rexx code.
Build a small scratch program with exits enabled, import rxfnsb, and call the BIF under TRACE R, TRACE I, TRACE ASM, or TRACE LLM.
If the trace needs to include standard-library frames, add TRACE UNSUPPRESS NAMESPACE rxfnsb before the call. The default TRACE filter hides rxfnsb and _rxsysb so ordinary user traces are not dominated by runtime-library internals.
For native or linked-image debugging, keep source/TRACE debug metadata in the linked image. The crexx -native driver strips that metadata by default; use --link-keep-source for a debuggable linked intermediate.

The functional BIF test target is testbifs, and the individual tests are named ts_*_noopt and ts_*_opt. The system plugin smoke test is named test_system.

JSON, Sockets, and HTTP

The Level B library includes small, stable building blocks for integration work:

rxjson: string-oriented JSON validation, path lookup, quoting, arrays, and objects
rxsocket: VM-backed TCP sockets with optional TLS depending on build configuration
rxhttp: HTTP client support layered on rxsocket

These modules are intentionally modest. They provide enough transport and JSON support for current demos and integrations without claiming to be complete web frameworks.

ADDRESS and Trace Support

_address.rexx contains the Rexx-side ADDRESS protocol support used by command dispatch, redirects, sandboxes, function calls, and host-variable binding helpers.

trace.rexx contains the runtime trace/debugger support used by TRACE and by the experimental debugger work. User-facing traces suppress standard library, compiler-exit, runtime-support, and debugger namespaces by default, while TRACE SUPPRESS NAMESPACE, TRACE UNSUPPRESS NAMESPACE, and TRACE RESET NAMESPACES let a debugging session adjust that filter.

rxdb remains experimental for the Release 1 beta line. Treat it as a smoke-tested debugging aid, not as a supported full debugger contract.

Class Library

classlib is loaded by the crexx driver by default and is part of the beta surface, but its public contract should stay small until class-library tests and examples are expanded. Prefer documenting concrete, tested classes rather than broad promises.

Level G and LLM Work

rxfnsg contains early Level G class-shaped library work, including the LLM client modules used by demos. This is useful and real, but Level G itself is not the baseline user language for the Release 1 beta line.

Native Plugins

Native functions use the RXPA plugin architecture. Dynamic plugins can be loaded by the VM, and selected plugins can be statically linked into packaged executables depending on build configuration.

From Level B source, calls look the same whether the implementation is written in cRexx, rxas, or native code. The import and runtime library path decide which module or plugin is available.