Overview of External Procedures

External procedures let Quxlang call functions, methods, constructors, and field operations supplied by a native library or managed runtime.

Native symbol calls

::malloc INCLUDE_IF(ENVIRONMENT_IS_GLIBC)
  EXTERN_PROCEDURE["glibc":"malloc" VERSION "GLIBC_2.2.5"]
  CALLABLE CALLCONV CCALL(@bytes SZ; RETURN ADDRESS);

The bracket identifies the library and symbol. CALLABLE describes the Quxlang parameters and result. CALLCONV CCALL selects the C calling convention, while VERSION records a required symbol version.

Optional symbols

::optional_extension INCLUDE_IF(ENVIRONMENT_IS_GLIBC)
  EXTERN_PROCEDURE["extension":"try_feature" OPTIONAL]
  CALLABLE(@value I32; RETURN I32);

OPTIONAL permits the symbol to be missing from the external environment. It does not make an unconditional call valid, so code must still establish that the selected target and runtime provide the symbol before calling it.

Managed-runtime operations

::system_out INCLUDE_IF(ARCH_IS_JVM)
  EXTERN_PROCEDURE["java/lang/System":"out"]
  CALLABLE CALLCONV JVM_GETSTATIC(; RETURN ~>java_print_stream);

::java_point_constructor INCLUDE_IF(ARCH_IS_JVM)
  EXTERN_PROCEDURE["java/awt/Point":"<init>"]
  CALLABLE CALLCONV JVM_CONSTRUCTOR(
    @x I32, @y I32; RETURN ~>java_point
  );

Other JVM conventions cover static, virtual, and interface calls plus instance and static field reads and writes. Their @THIS and @VALUE parameters state which object or value participates in the operation.

External procedure declarations are ABI contracts. Target predicates must restrict each declaration to targets that provide the required library, runtime, and calling convention.

See External Types for managed object types and Call Arguments for named arguments.

Reference

See the External Procedures Reference for declaration grammar, ABI options, and every managed calling convention.