Merge branch 'Umur-develop' into Umur-reducer-dev

CONTRIBUTING.md

@@ -8,7 +8,7 @@ Squiggle is currently pre-alpha.
 
 # Quick links
 
-- [Roadmap to the alpha](https://github.com/QURIresearch/squiggle/projects/2)
+- [Roadmap to the alpha](https://github.com/orgs/quantified-uncertainty/projects/1)
 - The team presently communicates via the **EA Forecasting and Epistemics** slack (channels `#squiggle` and `#squiggle-ops`), you can track down an invite by reaching out to Ozzie Gooen
 - [Squiggle documentation](https://www.squiggle-language.com/docs/Language)
 - [Rescript documentation](https://rescript-lang.org/docs/manual/latest/introduction)
@@ -20,10 +20,9 @@ Anyone (with a github account) can file an issue at any time. Please allow Quinn
 
 # Project structure
 
-Squiggle is a **monorepo** with four **packages**.
+Squiggle is a **monorepo** with three **packages**.
 
 - **components** is where we improve reactive interfacing with Squiggle
-- **playground** is the site `playground.squiggle-language.com`
 - **squiggle-lang** is where the magic happens: probability distributions, the interpreter, etc.
 - **website** is the site `squiggle-language.com`
 
@@ -41,13 +40,17 @@ We aspire for `ci.yaml` and `README.md`s to be in one-to-one correspondence.
 
 ## If you're on NixOS
 
-You'll need to run a command like this in order to get `yarn build` to run, especially in `packages/squiggle-lang`.
+You can't run `yarn` outside of a FHS shell. Additionally, you need to `patchelf` some things. A script does everything for you.
 
 ```sh
-patchelf --set-interpreter $(patchelf --print-interpreter $(which mkdir)) ./node_modules/gentype/gentype.exe
+./nixos.sh
 ```
 
-See [here](https://github.com/NixOS/nixpkgs/issues/107375)
+Reasons for this are comments in the script. Then, you should be able to do all the package-level `yarn run` commands/scripts. 
+
+# Try not to push directly to develop
+
+If you absolutely must, please prefix your commit message with `hotfix: `. 
 
 # Pull request protocol
 

packages/website/docs/Internal/Grammar.md

@@ -0,0 +1,56 @@
+---
+title: Grammar
+author:
+  - Quinn Dougherty
+---
+
+Formal grammar specification, reference material for parser implementation.
+
+_In all likelihood the reference will have to be debugged as we see what tests pass and don't pass during implementation_.
+
+## Lexical descriptions of constants and identifiers
+
+```
+<number> ::= [-]? [0-9]+ (.[0-9]+)? | [-]? [0-9]+ (.[0-9]+)? [e] [-]? [0-9]+
+<symbol> ::= [a-zA-Z]+ [a-zA-Z0-9]?
+<bool> ::= true | false
+```
+
+## Expressions
+
+The following gives no typing information. You can obey the grammar and still write nonsensical code.
+
+Think of javascript's list unpacking notation to read our variable-argument function `mixture`.
+
+```
+<expr> ::= <term> + <expr> | <term> - <expr> | <expr> .+ <expr> | <expr> .- <expr> | <term>
+<term> ::= <power> * <term> | <power> / <term> | <power> .* <term> | <power ./ <term> | <power>
+<power> ::= <factor> ^ <power> | <factor> .^ <power> | <factor>
+<factor> ::= <number> | <bool> | <symbol> | ( <expr> ) | <array> | <record> | <record>.<symbol> | <symbol> => <expr> | <symbol>(<symbol>) | <symbol>(<symbol>, <symbol>) | ...
+```
+
+## Data structures
+
+```
+<array> ::= [] | [<expr>] | [<expr>, <expr>] | ...
+<record> ::= {} | {<symbol>: <expr>} | {<symbol>: <expr>, <symbol>: <expr>} | ...
+```
+
+## Statements
+
+```
+<statement> ::= <assign> | <assignFunction>
+<assign> ::= <symbol> = <expr>
+<assignFunction> ::= <symbol>(<symbol>) = <expr> | <symbol>(<symbol>, <symbol>) = <expr> | ...
+```
+
+## A squiggle file
+
+To be valid and raise no errors as of current (apr22) interpreter,
+
+```
+<delim> ::= ; | \n
+<code> ::= <expr> | <statement> <delim> <expr> | <statement> <delim> <statement> <delim> <expr> | ...
+```
+
+This isn't strictly speaking true; the interpreter allows expressions outside of the final line.