TSE (The Semware Editor) – a general purpose plain text editor from Semware Corporation.
The editor’s key feature is, that its makers created a procedural programming language of editing commands, wrote the editor in that language, and made the language available to users. This makes the editor itself quite extendible and adaptable, and allows for creating text oriented tools more easily and quickly than with a generic programming language.
The programming language is called the Semware Application Language (SAL) and is referred to as the editor’s macro language. Up to and including TSE 4.4 it is well documented in the editor’s internal Help system, which is a delight to use. The language is compiled into intermediate code that is interpreted by the editor’s core, and comes with a good interactive debugger.
Alas, while TSE is still being maintained, it is no longer actively being developed. Its last commercial release was TSE Pro v4.4 in 2005. From 2005 to 2021 there was a closed beta. In 2022 it became publicly available, with a new license that grants broad permissions for its use and distribution and disclaims any warranty and liability. The former beta brought non-beta users 15 years of bug fixes and small improvements. The editor still does not natively support Unicode and paths/files longer than 255 characters, and has other, more minor functional and programming language limitations.
Using its macro programming language users have written extensions for its standard functionality (including Unicode extensions), as well as tools to perform both small and major editing tasks.