These are just notes written by one or more users of Epigram (currently just one user). They may or may not be correct, they may contain bogus explanations, etc. Use at your own risk. Feel free to edit this wiki to add or correct information - and don't be afraid to ask questions on the wiki, either - although if no-one who reads the wiki knows the answer, you might not get one. (See the end of the page for instructions on gaining access.)

All the information on this wiki currently relates to the prototype system Epigram 1, unless otherwise stated.

Epigram Links

Main epigram site - note that the old site at Durham University is out of date and should be ignored. The new site is hosted at Nottingham University (nott.ac.uk), and is visible from two addresses (e-pig.org and somewhere under nott.ac.uk).

Download page - if this link does not work, try the main site above

Glossary

Glossary of terminology used in the Epigram documentation

Warnings

• DON'T mix up CTRL+ALT+Enter (restart Epigram) and CTRL+ALT+Backspace (force-quits the X server, on many systems!) This is a good test to see if you are awake and sober, I guess...

How to...

• Quickly create a template for a data declaration: Type data into a shed and press ESC.

• Open a file: This is a slightly laborious four-step process at present:

1. Unless you want Epigram to insert the new file into its buffer alongside any other stuff that's there already, you'll want to press CTRL+ALT+Enter in the Epigram buffer, to clear it. (Don't forget the warning above about not mixing up CTRL+Alt+Enter with a certain three-finger salute!)
2. Open the file in a normal XEmacs way. For example, press the Open button, and click with the middle mouse button or mouse wheel on the file or directory you want to open. (If you have only two mouse buttons and no mouse wheel, try clicking both mouse buttons at exactly the same time - although this will only work if your X server has been set up to emulate 3 buttons in this way. If you have only one mouse button, I pity you.) XEmacs does not exactly match most people's definition of "user-friendly", so get used to it.
3. Transfer the file you've just loaded into an empty shed, by pressing CTRL+C twice. (XEmacs will just say something like "Mark set" in the status bar when you do this.)
4. Go back to the Epigram buffer by selecting it from the Buffers menu. The Epigram buffer should now have all of your file inside a shed. You may now want to press ESC.

• Save a file: You can (at least on my installation) save an Epigram buffer directly - but it's definitely not recommended, because then the Epigram buffer takes on the name of the file - and that complicates things if you want to reopen that file later in the same session. So, don't do that. Instead:

1. If you already have opened a buffer for the file you want to save, switch to that buffer with the Buffer menu. Otherwise, press the Open button and either type the name of a new file, or select the file you want to overwrite (no opportunity to confirm the overwrite will be given, so choose carefully!)
2. You will now be dumped into the new buffer. Press CTRL+C then CTRL+E to copy the contents of the Epigram buffer into your new buffer.
3. Press the Save button.
4. Switch back to the Epigram buffer by selecting it from the Buffers menu.
5. The next time you want to save to that same file in the same session, you don't need to open it again, because it's still open. You will find it on the Buffers menu (unless you deleted the buffer for that file).

• Edit text that has ESCaped from a shed Once typechecked, text cannot be edited, except by undoing the type checking. You can in theory press undo (Alt+Backspace) up to the point where the position that you want to do editing at was inside a shed. But this is hardly satisfactory - in some cases this would involve deleting your work (!), so in practice, at the moment - in the absence of a so-called "local undo" feature (see page 4 of the manual) - it is necessary to do at least some editing in an ordinary XEmacs buffer, and then bring it back into Epigram with CTRL+C CTRL+C. (Or, if you're so inclined, you can restart the type-checking process by saving and reloading your file.) See also section 2.3 of the manual.

Still to be written

Here are some ideas for things it would be nice to see on this wiki.

• But what does it all mean? - a gentle, colour-coded tour of the syntax for the lost and bewildered - assuming no knowledge of type theory, and even no knowledge of functional programming.

• WhistlestopTourOfTypeTheory - Teach type theory in 5 minutes.

• WhistlestopTourOfCategoryTheory - Teach category theory in 10 minutes.

References

• Keystrokes and mouse actions: You should find a summary of keystrokes and mouse actions at end of the user manual.

Introduction

• WhatWikiIs - history and explanation
• WikiStyle - find out how to edit wikis
• SandBox - play around here to figure out how to edit wiki pages
• NOTE: To edit this page, you will need to drop a note to the wiki admin at greenrd@greenrd.org to request the edit password for the Epigram wiki. In this note you must agree that all of your changes will be freely and irrevocably available to the world under the GNU Free Documentation License. (In future we may have individual passwords for each user, but for now, there is just one single password.)