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我跟着文檔,並嘗試:解析JSON動態與Data.Aeson
let st = do result <- decode "{\"name\":\"Dave\",\"age\":2}" --bss
flip parseMaybe result $ \obj -> do
name <- obj .: "name"
return name
我得到:
沒有實例(FromJSON B0)從使用的
.:' In a stmt of a 'do' block: name <- obj .: "name" In the expression: do { name <- obj .: "name"; return name } In the second argument of
產生($)」,即'\ obj - > do {name < - obj。:「name」; return name}'
如何正確地做到這一點?我究竟做錯了什麼?