With derive compiled and installed I thought I would change the code
a bit and try it...
ghci -fth -v0 -e '$( _derive_print_instance makeFunParser
'"''"'Foo )' baz.hs
baz.hs:30:3: Not in scope: `a1'
Any help is appreciated!
Thanks, Joel
---
FunParser.hs:
module FunParser where
import Data.Derive
import Data.Derive.Peephole
import Data.List
import Text.ParserCombinators.Parsec ( CharParser )
makeFunParser = Derivation drv "FunParser"
drv dat@(DataDef name arity ctors) =
simple_instance "FunParser" dat [funN "parse" [ sclause [] body ] ]
where
body = l1 "choice" $ lst [ clause con | con <- ctors ]
clause con = l1 "reserved" (lit (trim (ctorName con)))
>>: args con (ctorArity con)
trim = reverse . takeWhile (/= '.') . reverse
args ct 0 = return' (ctp ct 'a')
args ct k = l1 "char" (lit '(') >>: args' ct k 0
args' ct remn seen = l0 "parse"
>>=: (('a' : show seen)
->: args'' ct (remn-1) (seen+1))
args'' ct 0 seen = l1 "char" (lit ')') >>: return' (ctp ct 'a')
args'' ct k seen = l1 "char" (lit ',') >>: args' ct k seen
class FunParser a
where parse :: CharParser s a
baz.hs:
import Text.ParserCombinators.Parsec hiding ( parse )
import qualified Text.ParserCombinators.Parsec.Token as T
import Text.ParserCombinators.Parsec.Language( emptyDef )
import Data.Derive.TH
import FunParser
data NumExpr
= Int Integer
| Num Double
instance FunParser NumExpr where
parse = numExpr
data Foo
= Foo NumExpr
lexer = T.makeTokenParser emptyDef
identifier = T.identifier lexer
reserved = T.reserved lexer
integer = T.integer lexer
float = T.float lexer
numExpr :: GenParser Char a NumExpr
numExpr =
choice [ integer >>= return . Int
, float >>= return . Num
]
$( derive makeFunParser ''Foo )
--
http://wagerlabs.com/
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