Some fixes to the EBNF grammar

schala-lang/language/src/parsing.rs

@@ -3,8 +3,10 @@
 //!
 //!
 //! # Schala EBNF Grammar 
-//! Terminal productions are in 'single quotes' or UPPERCASE if they are a class of tokens,
+//! This document is the authoritative grammar of Schala, represented in something approximating
-//! or otherwise not representable in ASCII.
+//! Extended Backus-Naur form. Terminal productions are in "double quotes", or UPPERCASE
+//! if they represent a class of tokens rather than an specific string, or are otherwise
+//! unreprsentable in ASCII.
 //!
 //! ## Top level structure
 //!
@@ -15,7 +17,9 @@
 //! block := "{" (statement delimiter)* "}"
 //! declaration := type_declaration | func_declaration | binding_declaration | impl_declaration
 //! ```
-//! ## Declarations - Types
+//! ## Declarations
+//!
+//! ### Types
 //! ```
 //! type_declaration := "type" type_declaration_body
 //! type_declaration_body := "alias" type_alias | "mut"? type_singleton_name "=" type_body
@@ -25,8 +29,8 @@
 //! typed_identifier_list := typed_identifier*
 //! typed_identifier := IDENTIFIER type_anno
 //! ```
-//! ## Declaration - Functions 
+//! ### Functions
-//! 
+//!
 //! ```
 //! func_declaration := func_signature func_body
 //! func_body := ε | nonempty_func_body
@@ -36,29 +40,29 @@
 //! formal_param_list := "(" (formal_param ",")* ")"
 //! formal_param := IDENTIFIER type_anno+
 //! ```
-//! 
+//!
-//! ## Declaration - Variable bindings 
+//! ### Variable bindings
 //! ```binding_declaration := "let" "mut"? IDENTIFIER "=" expresion```
-//! 
+//!
-//! ## Declaration - Interface
+//! ### Interfaces
-//! 
+//!
 //! ```
 //! interface_declaration := "interface" type_singleton_name signature_block
 //! impl_declaration := "impl" type_singleton_name decl_block | "impl" type_singleton_name "for" type_name decl_block
 //! decl_block := "{" (func_declaration)* "}"
 //! signature_block := "{" (func_signature)* "}"
 //! ```
-//! 
+//!
-//! ## Type Annotations
+//! ### Type Annotations
-//! 
+//!
 //! ```
-//! type_anno := (":" type_name)+
+//! type_anno := ":" type_name
 //! type_name := type_singleton_name | "(" type_names ")"
 //! type_names := ε | type_name (, type_name)*
 //! type_singleton_name = IDENTIFIER (type_params)*
 //! type_params := "<" type_name (, type_name)* ">"
 //! ```
-//! 
+//!
 //! ## Expressions
 //! ```
 //! expression := precedence_expr type_anno+
@@ -66,26 +70,24 @@
 //! prefix_expr := prefix_op call_expr
 //! prefix_op := "+" | "-" | "!" | "~"
 //! call_expr := index_expr ( "(" expr_list ")" )* | ε
-//! ```
-//! 
-//! ```
 //! expr_list := expression ("," expression)* | ε
 //! index_expr := primary ( "[" (expression ("," (expression)* | ε) "]" )*
 //! primary := literal | paren_expr | if_expr | for_expr | while_expr | identifier_expr | lambda_expr | anonymous_struct | list_expr
+//! expr_or_block := "{" (statement delimiter)* "}" | expr
 //! ```
-//! 
+//!
-//! ## Primary expressions
+//! ### Primary expressions
-//! 
+//!
 //! ```
 //! list_expr := "[" (expression, ",")* "]"
-//! lambda_expr := "\\" lambda_param_list type_anno+ nonempty_func_body
+//! lambda_expr := "\" lambda_param_list type_anno+ nonempty_func_body
 //! lambda_param_list := formal_param_list |  formal_param
 //! paren_expr := LParen paren_inner RParen
 //! paren_inner := (expression ",")*
 //! identifier_expr := named_struct | IDENTIFIER
 //! ```
-//! 
+//!
-//! Expression literals
+//! ## Literals
 //! ```
 //! literal := "true" | "false" | number_literal | STR_LITERAL
 //! named_struct := IDENTIFIER record_block
@@ -93,7 +95,7 @@
 //! record_entry := IDENTIFIER ":" expression
 //! anonymous_struct := TODO
 //! ```
-//! 
+//!
 //! A `float_literal` can still be assigned to an int in type-checking
 //! ```
 //! number_literal := int_literal | float_literal
@@ -101,8 +103,8 @@
 //! float_literal := digits ("." digits)
 //! digits := (DIGIT_GROUP underscore)+
 //! ```
-//! 
+//!
-//! ## Patterns
+//! ### Patterns
 //! ```
 //! pattern := "(" (pattern, ",")* ")" | simple_pattern
 //! simple_pattern := pattern_literal | record_pattern | tuple_struct_pattern
@@ -112,12 +114,8 @@
 //! record_pattern_entry := IDENTIFIER | IDENTIFIER ":" Pattern
 //! tuple_struct_pattern := IDENTIFIER "(" (pattern, ",")* ")"
 //! ```
-//! 
+//!
-//! ```
+//! ### If-expressions
-//! expr_or_block := "{" (statement delimiter)* "}" | expr
-//! ```
-//! 
-//! ## If-expressions
 //! ```
 //! if_expr := "if" discriminator ("then" condititional | "is" simple_pattern_match | guard_block)
 //! discriminator := precedence_expr (operator)+
@@ -128,16 +126,16 @@
 //! guard_arm := guard "->" expr_or_block
 //! guard := "is" pattern | (operator)+ precedence_expr
 //! ```
-//! 
+//!
-//! ## While expressions
+//! ### While expressions
 //! ```
 //! while_expr := "while" while_cond "{" (statement delimiter)* "}"
 //! while_cond := ε | expression | expression "is"  pattern //TODO maybe is-expresions should be primary
 //! ```
-//! 
+//!
 //! //TODO this implies there must be at least one enumerator, which the parser doesn"t support right
 //! //this second, and maybe should fail later anyway
-//! ## For-expressions
+//! ### For-expressions
 //! ```
 //! for_expr := "for" (enumerator | "{" enumerators "}") for_expr_body
 //! for_expr_body := "return" expression |  "{" (statement delimiter)* "}"