Horns 0.4 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The software lies within Development Tools, more precisely IDE.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The most popular version among Horns users is 0.4. The Horns installer is commonly called horns.exe. This free program is a product of YelloSoft.
From the developer:
Horns is a minimal Lisp implementation. Its primary goal is to manipulate lambda expressions in an interpretive environment.
Horns is extremely regular and therefore (i) easy to parse, (ii) easy to debug, and (iii) easy to learn. The grammar is an LALR based on S-expressions as specified in horns.y. This file is both the implementation and specification for the language.
You may want to check out more software, such as Heroes of Might and Magic® III: Horn of The Abyss, AJHorn or DAL Flute Woodwinds VST VST3 AU, which might be related to Horns.