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|
module Decoder.Generic exposing (combine, pair, resultToDecoder, subdecode, tail, withDefault)
import Json.Decode as D exposing (Decoder)
withDefault : a -> Decoder a -> Decoder a
withDefault fallback decoder =
D.oneOf
[ decoder
, D.succeed fallback
]
combine : List (Decoder a) -> Decoder (List a)
combine =
List.foldr (D.map2 (::)) (D.succeed [])
subdecode : Decoder a -> D.Value -> Decoder a
subdecode d v =
D.decodeValue d v |> resultToDecoder
tail : Decoder a -> Decoder (List a)
tail itemDecoder =
D.list D.value
|> D.andThen
(\l ->
case l of
[] ->
D.fail "Can't get tail of empty"
head :: t ->
List.map (subdecode itemDecoder) t |> combine
)
pair : Decoder a -> Decoder b -> Decoder ( a, b )
pair aDecoder bDecoder =
D.map2 Tuple.pair
(D.index 0 aDecoder)
(D.index 1 bDecoder)
resultToDecoder : Result D.Error a -> Decoder a
resultToDecoder res =
case res of
Ok a ->
D.succeed a
Err e ->
D.fail (D.errorToString e)
|
