4878192 · elk · git.iko.soy

git.iko.soy/elk

Add nice error message for bad cyclic definitions

commit48781925fed2fa78b6811fedcebc30a4d5edf1e9 authorEvan Czaplicki <evancz@users.noreply.github.com> dateWed 31 Jan 2018, 22:20 (9 years ago) parentac7f11f

2 files changed+39−2

compare with master

unifiedsplit

src/Generate/JavaScript.hs+25−2 src/Generate/JavaScript/Builder.hs+14

src/Generate/JavaScript.hs+25−2

@@ -28,6 +28,7 @@ import qualified Elm.Name as N

2828import qualified Generate.JavaScript.Builder as JS

2929import qualified Generate.JavaScript.Expression as Expr

3030import qualified Generate.JavaScript.Name as Name

31+import qualified Reporting.Helpers as H

3132

3233

3334

@@ -224,9 +225,19 @@ generateCycle mode (Opt.Global home _) cycle =

224225 let

225226 safeDefs = map (generateSafeCycle mode home) cycle

226227 realDefs = map (generateRealCycle home) cycle

227− -- TODO add `try` in debug mode nice infinite recursion reports

228+ block = JS.Block (safeDefs ++ realDefs)

228229 in

229− JS.Block (safeDefs ++ realDefs)

230+ case mode of

231+ Name.Prod _ _ ->

232+ block

233+

234+ Name.Debug _ ->

235+ JS.Try block Name.dollar $ JS.Throw $ JS.String $

236+ "The following top-level definitions are causing infinite recursion:\\n"

237+ <> drawCycle (map fst cycle)

238+ <> "\\n\\nThese errors are very tricky, so read "

239+ <> B.stringUtf8 (H.makeLink "halting-problem")

240+ <> " to learn how to fix it!"

230241

231242

232243generateSafeCycle :: Name.Mode -> ModuleName.Canonical -> (N.Name, Opt.Expr) -> JS.Stmt

@@ -248,6 +259,18 @@ generateRealCycle home (name, _) =

248259 ]

249260

250261

262+drawCycle :: [N.Name] -> B.Builder

263+drawCycle names =

264+ let

265+ topLine = "\\n ┌─────┐"

266+ nameLine name = "\\n │ " <> N.toBuilder name

267+ midLine = "\\n │ ↓"

268+ bottomLine = "\\n └─────┘"

269+ in

270+ mconcat (topLine : List.intersperse midLine (map nameLine names) ++ [ bottomLine ])

271+

272+

273+

251274

252275-- GENERATE KERNEL

253276

src/Generate/JavaScript/Builder.hs+14

@@ -67,6 +67,8 @@ data Stmt

6767 | Break (Maybe Name) -- break lab;

6868 | Continue (Maybe Name) -- continue lab;

6969 | Labelled Name Stmt -- lab: stmt

70+ | Try Stmt Name Stmt -- try stmt catch (x) stmt

71+ | Throw Expr -- throw expr;

7072 | Return (Maybe Expr) -- return expr;

7173 | Var [(Name, Maybe Expr)] -- var x, y=42;

7274 | FunctionStmt Name [Name] [Stmt] -- function f(x, y, z) {...}

@@ -210,6 +212,18 @@ fromStmt indent statement =

210212 , fromStmt indent stmt

211213 ]

212214

215+ Try tryStmt errorName catchStmt ->

216+ mconcat

217+ [ indent, "try {\n"

218+ , fromStmt (deeper indent) tryStmt

219+ , indent, "} catch (", Name.toBuilder errorName, ") {\n"

220+ , fromStmt (deeper indent) catchStmt

221+ , indent, "}\n"

222+ ]

223+

224+ Throw expr ->

225+ "throw " <> snd (fromExpr indent Whatever expr) <> ";"

226+

213227 Return Nothing ->

214228 indent <> "return;\n"

215229