Question 1

How do I type APL characters in April with Emacs?

Accepted Answer

Install the gnu-apl-mode plugin via MELPA or use John Thingstad's dedicated mode; then toggle APL input with C-\ and use prefixes like . for glyphs. This setup is detailed in the README's editor configuration sections.

Question 2

April vs Dyalog APL: what are the main differences?

Accepted Answer

April compiles APL to Common Lisp, enabling Lisp interoperability but missing some system functions, while Dyalog is a standalone APL with full features. April also adds unique extensions like k-style if-statements and has different lexical defaults (e.g., disclose function).

Question 3

Can April handle file input/output operations?

Accepted Answer

No, April does not implement APL's file I/O functions (e.g., ⍇, ⍈); the README states these are excluded because Common Lisp already provides system interaction tools, so you'd handle I/O outside of April.

Question 4

How do I pass a Lisp array to April for processing?

Accepted Answer

Use the :in parameter with (april), e.g., (april (with (:state :in ((my-array #(1 2 3))))) "myArray+5"). This allows seamless data flow from Lisp into APL expressions.

Question 5

Is April production-ready for data-intensive tasks?

Accepted Answer

It depends; April is stable and tested across Lisp implementations, but performance may vary due to compilation overhead. For critical applications, benchmark with your data sets and consider the trade-offs with native APL.

Question 6

What Common Lisp implementation works best with April?

Accepted Answer

SBCL and CCL are considered fully compatible with no special provisions, while others like ECL or ABCL require adjustments and have some limitations, as noted in the compatibility documentation.

April

What is April?

Overview

Use Cases

Best For

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions