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{
module Parser where
import Control.Monad.Error
import Lexer.Support
import Syntax
import Lexer (scan)
}
%name parseExpr Expr
%name parseDecl Decl
%tokentype { Token }
%monad { Lexer }
%lexer { lexer } { TkEOF }
%errorhandlertype explist
%error { parseError }
%token
VAR { TkIdent $$ }
'let' { TkLet }
'in' { TkIn }
'where' { TkWhere }
'=' { TkEqual }
'{' { TkOpen }
';' { TkSemi }
'}' { TkClose }
'\\' { TkBackslash }
'->' { TkArrow }
'(' { TkLParen }
')' { TkRParen }
OPEN { TkVOpen }
SEMI { TkVSemi }
CLOSE { TkVClose }
%%
Atom :: { Expr }
: VAR { Var $1 }
| '(' Expr ')' { $2 }
Expr :: { Expr }
: '\\' VAR '->' Expr { Lam $2 $4 }
| 'let' DeclBlock 'in' Expr { Let $2 $4 }
| FuncExpr { $1 }
FuncExpr :: { Expr }
: FuncExpr Atom { App $1 $2 }
| Atom { $1 }
DeclBlock :: { [Decl] }
: '{' DeclListSemi '}' { $2 }
| OPEN DeclListSEMI Close { $2 }
DeclListSemi :: { [Decl] }
: Decl ';' DeclListSemi { $1:$3 }
| Decl { [$1] }
| {- empty -} { [] }
DeclListSEMI :: { [Decl] }
: Decl SEMI DeclListSemi { $1:$3 }
| Decl { [$1] }
| {- empty -} { [] }
Close
: CLOSE { () }
| error {% popLayout }
Decl
: VAR '=' Expr { Decl $1 $3 Nothing }
| VAR '=' Expr 'where' DeclBlock { Decl $1 $3 (Just $5) }
{
lexer cont = scan >>= cont
parseError = throwError . show
}