git.iko.soy/elk
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elk/src/Reporting/Error/Syntax.hs
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1{-# OPTIONS_GHC -Wall #-}
2module Reporting.Error.Syntax where
4import qualified Data.List as List
5import qualified Data.Set as Set
6import qualified Text.Parsec.Error as Parsec
7import Text.PrettyPrint.ANSI.Leijen (dullyellow, hsep, text)
9import qualified Reporting.Error.Helpers as Help
10import qualified Reporting.Render.Type as RenderType
11import qualified Reporting.Report as Report
14data Error
15 = Parse [Parsec.Message]
16 | BadFunctionName Int
17 | BadPattern String
19 | CommentOnNothing
21 | SettingsOnNormalModule
22 | SettingsOnPortModule
23 | DuplicateSettingOnEffectModule String
24 | BadSettingOnEffectModule String
25 | NoSettingsOnEffectModule
26 | MissingManagerOnEffectModule String
27 | UnexpectedPort String
29 | TypeWithoutDefinition String
31 | DuplicateArgument String String
32 | DuplicateFieldName String
33 | DuplicateValueDeclaration String
34 | DuplicateTypeDeclaration String
35 | DuplicateDefinition String
36 | UnboundTypeVarsInUnion String [String] [String]
37 | UnboundTypeVarsInAlias String [String] [String]
38 | UnusedTypeVarsInAlias String [String] [String]
39 | MessyTypeVarsInAlias String [String] [String] [String]
42-- TO REPORT
44toReport :: RenderType.Localizer -> Error -> Report.Report
45toReport _localizer err =
46 case err of
47 Parse messages ->
48 parseErrorReport messages
50 BadFunctionName arity ->
51 Report.report
52 "BAD FUNCTION DEFINITION"
53 Nothing
54 "Complex patterns cannot be used as function names."
55 ( Help.reflowParagraph $
56 "This function definition has " ++ show arity ++ " arguments, but instead\
57 \ of a normal name like `add` or `reverse` it has a pattern. There is no\
58 \ way to \"deconstruct\" a function with pattern matching, so this needs to\
59 \ be changed to a normal name."
60 )
62 BadPattern name ->
63 Report.report
64 "BAD PATTERN"
65 Nothing
66 ("The free variable `" ++ name ++ "` appears more than once in this pattern.")
67 ( Help.stack
68 [ text "Rename the variables so there are no duplicates."
69 , Help.reflowParagraph $
70 "In Elm, pattern matching works by binding these free variables to subsections\
71 \ of the matching value. It does not make sense to have the same name for two\
72 \ different subsections though! When you say `" ++ name ++ "` in some code, there\
73 \ is no way for me to know which subsection you mean!"
74 ]
75 )
77 CommentOnNothing ->
78 Report.report
79 "STRAY COMMENT"
80 Nothing
81 ("This documentation comment is not followed by anything.")
82 ( Help.reflowParagraph $
83 "All documentation comments need to be right above the declaration they\
84 \ describe. Maybe some code got deleted or commented out by accident? Or\
85 \ maybe this comment is here by accident?"
86 )
88 SettingsOnNormalModule ->
89 Report.report
90 "BAD MODULE DECLARATION"
91 Nothing
92 "A normal module can expose values, but not settings like this."
93 ( Help.reflowParagraph $
94 "If you want a normal module, just remove this stuff. If you want to create\
95 \ an `effect module` you just forgot to use the `effect` keyword. In that\
96 \ case, just change `module` to `effect module` and you should be headed in\
97 \ the right direction!"
98 )
100 SettingsOnPortModule ->
101 Report.report
102 "BAD MODULE DECLARATION"
103 Nothing
104 "A port module can expose values, but not have settings like this."
105 ( Help.reflowParagraph $
106 "If you want a port module, just remove this stuff. If you want to create\
107 \ a custom effect module instead (which is rare) just change `port module`\
108 \ to `effect module` and you should be headed in the right direction!"
109 )
111 DuplicateSettingOnEffectModule name ->
112 Report.report
113 "EFFECT MODULE PROBLEM"
114 Nothing
115 ("You have defined " ++ Help.functionName name ++ " multiple times.")
116 ( Help.reflowParagraph $
117 "There can only be one " ++ Help.functionName name
118 ++ " though! Remove until there is one left."
119 )
121 BadSettingOnEffectModule name ->
122 Report.report
123 "EFFECT MODULE PROBLEM"
124 Nothing
125 ("Setting " ++ Help.functionName name ++ " is not recognized.")
126 ( Help.reflowParagraph $
127 "Remove this entry and you should be all set!"
128 )
130 NoSettingsOnEffectModule ->
131 Report.report
132 "EFFECT MODULE PROBLEM"
133 Nothing
134 ("You are defining an effect module, but it has no settings.")
135 ( Help.reflowParagraph $
136 "If you just wanted a normal module, change the keywords `effect module`\
137 \ to `module` and you should be all set. If you want a proper effect module,\
138 \ you need to specify your commands and/or subscriptions. Read more about this\
139 \ here: <http://guide.elm-lang.org/effect_managers/>"
140 )
142 MissingManagerOnEffectModule name ->
143 Report.report
144 "EFFECT MODULE PROBLEM"
145 Nothing
146 ("You are defining an effect module, but there is no " ++ Help.functionName name ++ " defined.")
147 ( Help.reflowParagraph $
148 "There is a small set of top-level functions and values that must be defined\
149 \ in any complete effect module. The best thing is probably to just read more\
150 \ about effect modules here:\
151 \ <http://guide.elm-lang.org/effect_managers/>"
152 )
154 UnexpectedPort name ->
155 Report.report
156 "BAD PORT"
157 Nothing
158 ("You are declaring port " ++ Help.functionName name ++ " in a normal module.")
159 ( Help.reflowParagraph $
160 "All ports must be defined in a `port module`. You should probably have just\
161 \ one of these for your project. This way all of your foreign interactions\
162 \ stay relatively organized."
163 )
165 TypeWithoutDefinition valueName ->
166 Report.report
167 "MISSING DEFINITION"
168 Nothing
169 ("There is a type annotation for `" ++ valueName ++ "` but there"
170 ++ " is no corresponding definition!"
171 )
172 ( text $
173 "Directly below the type annotation, put a definition like:\n\n"
174 ++ " " ++ valueName ++ " = 42"
175 )
177 DuplicateArgument funcName argName ->
178 Report.report
179 "DUPLICATE ARGUMENT"
180 Nothing
181 ( "The name `" ++ argName
182 ++ "` is used more than once in the arguments of `"
183 ++ funcName ++ "`."
184 )
185 ( Help.reflowParagraph $
186 "Rename things until `" ++ argName ++ "` is used only once.\
187 \ Otherwise how can we tell which one you want when you\
188 \ say `" ++ argName ++ "` it in the body of your function?"
189 )
191 DuplicateFieldName name ->
192 Report.report
193 "DUPLICATE FIELD"
194 Nothing
195 ("This record has more than one field named `" ++ name ++ "`.")
196 (text "There can only be one. Do some renaming to make sure the names are distinct!")
198 DuplicateValueDeclaration name ->
199 Report.report
200 "DUPLICATE DEFINITION"
201 Nothing
202 ( "Naming multiple top-level values `" ++ name ++ "` makes things\n"
203 ++ "ambiguous. When you say `" ++ name ++ "` which one do you want?"
204 )
205 ( Help.reflowParagraph $
206 "Find all the top-level values named " ++ Help.functionName name
207 ++ " and do some renaming. Make sure the names are distinct!"
208 )
210 DuplicateTypeDeclaration name ->
211 Report.report
212 "DUPLICATE DEFINITION"
213 Nothing
214 ( "There are multiple types named `" ++ name ++ "` in this module."
215 )
216 ( Help.reflowParagraph $
217 "Search through this module, find all the types named `" ++ name
218 ++ "`, and give each of them a unique name."
219 )
221 DuplicateDefinition name ->
222 Report.report
223 "DUPLICATE DEFINITION"
224 Nothing
225 ("There are multiple values named `" ++ name ++ "` in this let-expression."
226 )
227 ( Help.reflowParagraph $
228 "Search through this let-expression, find all the values named `" ++ name
229 ++ "`, and give each of them a unique name."
230 )
232 UnboundTypeVarsInUnion typeName givenVars unbound ->
233 unboundTypeVars "type" typeName givenVars unbound
235 UnboundTypeVarsInAlias typeName givenVars unbound ->
236 unboundTypeVars "type alias" typeName givenVars unbound
238 UnusedTypeVarsInAlias typeName givenVars unused ->
239 Report.report
240 "UNUSED TYPE VARIABLES"
241 Nothing
242 ( "Type alias `" ++ typeName ++ "` cannot have unused type variables: "
243 ++ Help.commaSep unused
244 )
245 ( Help.stack
246 [ text "You probably need to change the declaration like this:"
247 , dullyellow $ hsep $
248 map text ("type" : "alias" : typeName : filter (`notElem` unused) givenVars ++ ["=", "..."])
249 ]
250 )
252 MessyTypeVarsInAlias typeName givenVars unused unbound ->
253 Report.report
254 "TYPE VARIABLE PROBLEMS"
255 Nothing
256 ( "Type alias `" ++ typeName ++ "` has some problems with type variables."
257 )
258 ( Help.stack
259 [ Help.reflowParagraph $
260 "The declaration says it uses certain type variables ("
261 ++ Help.commaSep unused ++ ") but they do not appear in the aliased type. "
262 ++ "Furthermore, the aliased type says it uses type variables ("
263 ++ Help.commaSep unbound
264 ++ ") that do not appear in the declaration."
265 , text "You probably need to change the declaration like this:"
266 , dullyellow $ hsep $
267 map text ("type" : "alias" : typeName : filter (`notElem` unused) givenVars ++ unbound ++ ["=", "..."])
268 ]
269 )
272unboundTypeVars :: String -> String -> [String] -> [String] -> Report.Report
273unboundTypeVars declKind typeName givenVars unboundVars =
274 Report.report
275 "UNBOUND TYPE VARIABLES"
276 Nothing
277 ( Help.capitalize declKind ++ " `" ++ typeName ++ "` must declare its use of type variable"
278 ++ Help.commaSep unboundVars
279 )
280 ( Help.stack
281 [ text "You probably need to change the declaration like this:"
282 , hsep $
283 map text (declKind : typeName : givenVars)
284 ++ map (dullyellow . text) unboundVars
285 ++ map text ["=", "..."]
286 , Help.reflowParagraph $
287 "Here's why. Imagine one `" ++ typeName ++ "` where `" ++ head unboundVars ++
288 "` is an Int and another where it is a Bool. When we explicitly list the type\
289 \ variables, the type checker can see that they are actually different types."
290 ]
291 )
295-- TAGGING PARSE ERRORS
298newline :: String
299newline = "NEWLINE"
302freshLine :: String
303freshLine = "FRESH_LINE"
306whitespace :: String
307whitespace = "WHITESPACE"
310tab :: String
311tab = "TAB"
314keyword :: String -> String
315keyword kwd =
316 "KEYWORD=" ++ kwd
319prime :: String -> String
320prime var =
321 "PRIME=" ++ var
324data SpecialMessage
325 = MsgKeyword String
326 | MsgPrime String
327 | MsgTab
330extractSpecialMessage :: String -> Maybe SpecialMessage
331extractSpecialMessage message =
332 if List.isPrefixOf "KEYWORD=" message then
333 Just $ MsgKeyword (drop (length "KEYWORD=") message)
335 else if List.isPrefixOf "PRIME=" message then
336 Just $ MsgPrime (drop (length "PRIME=") message)
338 else if tab == message then
339 Just MsgTab
341 else
342 Nothing
345-- REPORTING PARSE ERRORS
347parseErrorReport :: [Parsec.Message] -> Report.Report
348parseErrorReport messages =
349 let
350 addMsg message hint =
351 case message of
352 Parsec.SysUnExpect _msg ->
353 hint
355 Parsec.UnExpect _msg ->
356 hint
358 Parsec.Expect msg ->
359 let
360 msg' =
361 if msg `elem` [whitespace, newline, freshLine] then
362 "whitespace"
363 else
364 msg
365 in
366 if msg == tab then
367 -- Our parser looks for tab so it can throw a custom tab error message.
368 -- Exclude tabs from the list of expected tokens so that no one thinks they are supported.
369 hint
370 else
371 hint { _expected = Set.insert msg' (_expected hint) }
373 Parsec.Message msg ->
374 hint { _messages = msg : _messages hint }
376 (ParseHint msgs expects) =
377 foldr addMsg emptyHint messages
379 (preHint, maybePost) =
380 case msgs of
381 [msg] ->
382 case extractSpecialMessage msg of
383 Just (MsgKeyword kwd) ->
384 ( "It looks like the keyword `" ++ kwd ++ "` is being used as a variable."
385 , Just "Rename it to something else."
386 )
388 Just (MsgPrime var) ->
389 ( "Ran into a single quote in a variable name. This was removed in 0.18!"
390 , Just $
391 "Change it to a number or an underscore, like " ++ var ++ "_ or " ++ var
392 ++ "1\n\nOr better yet, choose a more descriptive name!"
393 )
395 Just MsgTab ->
396 ( "A tab character was found, but all whitespace (including indentation) must be spaces not tabs."
397 , Just "I am looking for spaces, not tabs."
398 )
400 Nothing ->
401 ( msg
402 , Nothing
403 )
405 _ ->
406 ( "I ran into something unexpected when parsing your code!"
407 , Nothing
408 )
410 postHint =
411 if Set.null expects then
412 "Maybe <http://elm-lang.org/docs/syntax> can help you figure it out."
414 else
415 "I am looking for one of the following things:\n"
416 ++ concatMap ("\n "++) (Set.toList expects)
417 in
418 Report.report
419 "SYNTAX PROBLEM"
420 Nothing
421 preHint
422 (text (maybe postHint id maybePost))
425data ParseHint = ParseHint
426 { _messages :: [String]
427 , _expected :: Set.Set String
428 }
429 deriving (Show)
432emptyHint :: ParseHint
433emptyHint =
434 ParseHint [] Set.empty