flowstdlib Library

flowstdlib is a standard library of functions and flows for flow programs to use.


flowstdlib contains the following modules:

Use by the Compiler

In order for the compiler to be able to find the library's flow and function definitions, the directory containing this library must be in the default location ($HOME/.flow/lib), be part of FLOW_LIB_PATH or specified using an instance of the -L command line option to flowc,

NOTE: That flows are compiled down to a graph of functions at compile time, and do not exist at runtime.

Building this library from Source

Libraries like flowstdlib are built using flowc, specifying the library root folder as the source url.

This builds a directory tree (in target/{lib_name}) of all required files for a portable library, including:-

  • documentation files (.md MarkDown files, .dot graphs of flows, graphs rendered as .dot.svg SVG files)
  • TOML definition files for flows and functions
  • Function implementations compiled to a .wasm WASM file
  • A manifest.json manifest of the libraries functions and where the implementations (.wasm files) can be found. This is used by the Runtime to be able to load it.

Dual nature of flow libraries

Flow libraries such as flowstdlib have a dual nature. They can compiled and linked natively to a binary such as flowr, or when compiled by flowc all the functions implementations are compiled to .wasm WASM files.

Native use by a Runtime

flowr offers the -n/--native option for the flowstdlib to be used natively. When used, functions it contains will be run natively (machine code), as opposed to WASM implementations of the functions.

WASM use by a Runtime

If the -n/--native option is not used, and the library manifest (manifest.json) is found by the flow runner (e.g. flowr) at runtime (using default location, FLOW_LIB_PATH or -L), then the manifest is read and the functions WASM implementations found and loaded.

When a job is executed that requires one of these library functions, the WASM implementation is run.


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