Sim

Sim aims to make circuit design as simple and fun as possible by using intuitive interfaces and powerful abstractions. Sim is created as a part of the Crafting Computer course.

Try the online Sim editor here!

Development

We welcome all questions, suggestions, issues, and pull requests.

Set up

• Follow instructions here to install Elm which is powers the Sim compiler and editor.
• Follow instructions here to install elm-live which is used for building and running Sim.

Commands

• Run editor:

sed -i 's+src="elm.js"+src="/public/elm.js"+' public/index.html
elm-live src/Editor.elm --start-page public/index.html -- --output=public/elm.js

• Build optimized version of editor:

./build.sh

Note: you may need to enable execution permission before running the command:

chmod +x ./build.sh

• Run Sim compiler on a source string:

elm-live src/Main.elm --start-page debug/index.html -- --output=debug/elm.js

Credits

Thanks to all the wonderful projects below that inspired Sim:

• Nand to Tetris
• Elm
• Type inference for beginners — Part 1

License

MIT

Change Log

Release v0.10.0

• Require at least one definition in defs, so no empty program or empty let...in expression
• Largely fix varSize inference, so stuff like below compiles

  test i[i] j[j] k[k] -> [j] =
  let
      a = nand i i
      b = nand j j
      c = nand k k
  in
  b

• Better fit values in truth table

Release v0.9.0

• Keep track of scope levels independent of indentations in emitter
• Add number format dropdown for truth table
• Show numbers in truth table in their sizes (pad 0 and 1 if needed)
• Detect mutual recursive definitions and emit specific outputs for them

Release v0.8.0

• Detect varSize casting problems (approach having decent type inference)
• Move tutorial to a separate ebook
• Make README specific to Sim

Release v0.7.0

• Constrain VarSize names to the function they are defined in
• Add ALU tutorial

Release v0.6.0

• Add concatenation operator (++)
• Fix binary parsing and display
• Fix line comment newline counting problem

Release v0.5.0

• Add busLiteral expression, e.g. [0, 1, 0, 0]
• Better generate and display truth tables of different sizes
• Lock caption and header of truth table when scrolling

Release v0.4.0

• Fix indentation checking for record, intLiteral, and bindingOrCall
• Detect binding record assignment mismatches
• Pop parameters and local names from context when out of scope
• Fix the emitted JS of indexing expr another time
• Fix indexing on IntSize type inference
• Filter out duplicated parser problems

Release v0.3.0

• Fix the emitted JS of indexing expr
• Fix EqualToSize comparison in unify
• Check for duplicated names

Release v0.2.0

• Properly show 2's complement in decimal in truth table
• Add fill function to prelude
• Allow spaces inside parenthesized group expr
• Fix some checker error messages

Release v0.1.0

• Store units in localStorage
• Can remove tabs
• Fix parse error underlining