From 0253cd7b3609f2d832c78e933521eaf63f7156cd Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Tue, 13 Oct 2020 18:07:22 -0600
Subject: some syntax work

---
 syntax.md | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 74 insertions(+), 7 deletions(-)

diff --git a/syntax.md b/syntax.md
index c0b043f..550fbcc 100644
--- a/syntax.md
+++ b/syntax.md
@@ -36,6 +36,7 @@ A *keyword* is one of the following literal words:
 - `extern`
 - `float`
 - `for`
+- `function`
 - `if`
 - `include`
 - `int`
@@ -161,10 +162,76 @@ A *block comment* begins with the characters `/*` if they occur outside of a str
 
 The syntax of Crowbar is given as a [parsing expression grammar](https://en.wikipedia.org/wiki/Parsing_expression_grammar):
 
-| Syntax Element   |   | Parsing Expression       |
-|:-----------------|:-:|:-------------------------|
-|ImplementationFile| ← |ImplementationFileElement*|
-|HeaderFile        | ← |HeaderFileElement*        |
-|HeaderFileElement | ← |IncludeStatement          |
-|                  | / |TypeDeclaration           |
-|                  | / |FunctionDeclaration       |
+## Entry points
+
+```
+HeaderFile                ← HeaderFileElement+
+HeaderFileElement         ← IncludeStatement /
+                            TypeDeclaration /
+                            FunctionDeclaration
+
+ImplementationFile        ← ImplementationFileElement+
+ImplementationFileElement ← HeaderFileElement /
+                            FunctionDefinition
+```
+
+## Top-level elements
+
+```
+IncludeStatement    ← 'include' string-literal ';'
+
+TypeDeclaration     ← StructDeclaration /
+                      EnumDeclaration
+StructDeclaration   ← 'struct' identifier '{' VariableDeclaration+ '}' ';'
+EnumDeclaration     ← 'enum' identifier '{' EnumItem+ '}' ';'
+EnumItem            ← identifier ','
+
+FunctionDeclaration ← FunctionSignature ';'
+FunctionDefinition  ← FunctionSignature Block
+FunctionSignature   ← Type identifier '(' Argument* ')'
+Argument            ← Type identifier ','
+```
+
+## Statements
+
+```
+Statement ←
+
+Block ← '{' Statement* '}'
+
+VariableDeclaration ← Type identifier ';'
+```
+
+## Types
+
+```
+Type        ← BasicType /
+              'const' BasicType /
+              BasicType '*' /
+              BasicType '[' Expression ']' /
+              Type 'function' '(' (BasicType ',')* ')'
+BasicType   ← 'void' /
+              IntegerType /
+              'signed' IntegerType /
+              'unsigned' IntegerType /
+              'float' /
+              'double' /
+              'bool' /
+              'struct' identifier /
+              'enum' identifier /
+              identifier /
+              '(' Type ')'
+IntegerType ← 'char' /
+              'short' /
+              'int' /
+              'long'
+```
+
+## Expressions
+
+```
+AssignmentTargetExpression ←
+Expression                 ←
+```
+
+[![Creative Commons BY-SA License](https://i.creativecommons.org/l/by-sa/4.0/80x15.png)](http://creativecommons.org/licenses/by-sa/4.0/)
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