Fructure: A structured interaction engine in Racket

Updated July 2019 : Installation instructions & mini-guide below

CLICK HERE for a video demo from RacketCon 2019

Fructure at RacketCon 2019.My talk (from the livestream).Slides: Real version. Extended unedited version.

Fructure is a prototype structure editor, which can currently be used to write & edit small programs in a small subset of scheme/racket. This is a personal project where I'm playing with ideas in editing, programming languages, and interaction design.

Note: now that this is getting some traffic I wanted to put up a disclaimer that some of the code is currently in a bit of a state: I've commented out some things and hacked up some others to smoothen the demo. My immediate plans are - after taking a post-racketcon break and aside from general cleanup - to unhackify the way transforms currently work, properly re-instate variadic parameters for binding forms, and do some profiling and address the current sluggishness.

• fig 1: walking the grammar

• fig 2: refactoring by re/destructuring

• fig 3: menu closeup

I wrote a bit about my then-current direction in September 2018, just before beginning my current implementation attempt. I've completed most of what I talk about there, with varying levels of success: Fructure 1 of 2 Fructure 2 of 2. There will soon be some slightly more up-to-date notes via my racketcon slides. For more updates cyberfollow @twitter and @elsewhere. Here's an ongoing dev screenshot dump; check out the chronological overview:

fig 4: family history

Installation Instructions

Basically, you need to install racket, a couple libraries, and a font if you don't want thing to look screwy.

MacOS:

1. brew install racket --cask
2. brew tap homebrew/cask-fonts && brew install font-iosevka --cask
3. raco pkg install memoize
4. raco pkg install rackjure
5. git clone https://github.com/disconcision/fructure.git

Linux, Windows: (under construction)

TO RUN:

1. cd fructure
2. racket src/fructure.rkt

FAQ: Q: Is it suppose to be this slow? A: It's open source.

Fructure Primer

STEP 0: What to do if you're stuck / Speedrun instructions

1. How to win: There are modes, but pressing ESC enough times should always get you to the base mode. From there, press SPACE to enter command mode. From here, PRESS "q" then RIGHT-ARROW to quit.
2. Check the terminal for silent crashes (aka 'bonus' victory conditions)

STEP 1: mini tutorial

Fructure starts in NAV(igation) mode. The selector (red) encloses a hole (yellow).

NAV keybindings

• ENTER toggles TRANSFORM mode

A transform (red) maps the source (the hole) to (->) the target (selection (outlined in red) in menu (also outlined in red))

TRANSFORM keybindings

• UP/DOWN move menu / selector: find and select an "if" expression)
• ENTER performs selected transform, toggles NAV mode: transform the hole to the if

NAV keybindings (continued)

• LEFT/RIGHT move selector in preorder tree traversal: go right thrice and left twice to cycle the selection, settling on the first child

These keys (almost) suffice to build/delete arbitrary syntax, though not terribly conveniently. Build a tiny program this way. I say almost because you can't (yet, owing to a bug) input new identifiers in this way. Doing so (currently) requires being in the menu and pressing RIGHT on a lambda or define (see next step).

STEP 2:

Approximating standard text-entry

NAV keybindings

• UP/DOWN selector to parent/first child

TRANSFORM keybindings

• ESC switch to NAV mode without performing transformation
• RIGHT step into current transform: (essentially) perform selected transform, and then advance the selector/menu to the first created hole. (unless last action was an undo, in which case RIGHT is a redo)
• LEFT undo (back to state at last step, delimited by entering transform mode)
• SPACE in current implementation the same as RIGHT, minus the redo part. eventually, it should be part of alphanumerics
• alphanumerics + ( + ) filter menu by search buffer prefix match
• BACKSPACE erase most recent character in search buffer
• DELETE erase search buffer

STEP 3:

Abstract copy/paste

NAV keybindings

• TAB capture selection
• ESC clear captures

TRANSFORM keybindings

• SHIFT-LEFT/RIGHT un/fold transform display
• SHIFT-UP/DOWN extend/contract displayed menu options

STEP 4:

Simple settings scrubber

NAV keybindings

• SPACE switch to COMMAND mode

TRANSFORM keybindings

• SHIFT-SPACE switch to COMMAND mode

COMMAND keybindings

• UP/DOWN select property
• LEFT/RIGHT scrub property
• alphanumerics/BACKSPACE/DELETE : filter/unfilter property
• ESC return to NAV or TRANSFORM mode

BOITE DIABOLIQUE: housing the 19 forbidden keybindings

EXPERIMENTAL & FICTIONAL keybindings: lies at best, trouble at worst

NAV

• F2 dump current structure to stdin
• CTRL-F9-F12 save structure to disk
• SHIFT-F9-F12 load structure from disk
• SHIFT-LEFT/RIGHT selector to sibling
• DOWN step into capture
• alphanumerics (restrict selector traversal to search buffer hits aka find as you type) TRANSFORM
• F2 dump current structure to stdin
• RCTRL shortcut to select/insert parens

Screenshots

Structured insertion via walking the grammar:

Navigation mode

Copy/Paste via Metavariables

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