This directory contains software packages implementing standard libraries for APL. For now, most of them have been ported from Dyalog's MIT-licensed collection of dfns.
You can include functions and operators from these libraries in an application using April with April's ⎕XWF and ⎕XWO syntax forms, used to load external functions and operators respectively.
The first step is typically to create an ASDF system depending on the library/libraries you wish to use, like so:
(asdf:defsystem #:my-system
:description "A system using April and its array processing function library."
:author "Me"
:license "..."
:serial t
:depends-on ("april" "april-lib.dfns.array")
:components (...files listed here...)This is an example of a system using the array processing library, which contains some of the most broadly useful functions. Let's say that you want to use the display and disp functions from that library so you can print neatly formatted representations of arrays using box-drawing characters. The next step is to invoke the following code:
display disp ← 'ARRAY-LIB-SPACE' ⎕XWF 'display' 'disp'This code can either be placed in an .apl file or in an (april) macro like so:
(april (with (:space my-workspace)) "display disp ← 'ARRAY-LIB-SPACE' ⎕XWF 'display' 'disp'")What this code does is create a pair of functions, display and disp in your workspace aliasing the functions display and disp in the workspace called array-lib-space that holds the array processing library functions. With this done you can use the libraries in April code:
* (april (with (:space my-workspace)) "⎕←disp ⍳4 5 ⋄ 'Drawing complete!'")
┌───┬───┬───┬───┬───┐
│1 1│1 2│1 3│1 4│1 5│
├───┼───┼───┼───┼───┤
│2 1│2 2│2 3│2 4│2 5│
├───┼───┼───┼───┼───┤
│3 1│3 2│3 3│3 4│3 5│
├───┼───┼───┼───┼───┤
│4 1│4 2│4 3│4 4│4 5│
└───┴───┴───┴───┴───┘
"Drawing complete!"And that's all there is to it. These examples assume that you've created a workspace called my-workspace to use within your application.