Better help for the user

- Clearer (more detailed) error messages (see parser.messages, parser_driver.ml ->)
	--> Parser_driver.ml : we're more precise and show all possible instructions to the user.
- Suggestions.ml : unimportant display changes + renaming

compiler/catala_utils/suggestions.ml

@@ -50,20 +50,20 @@ let levenshtein_distance (s : string) (t : string) : int =
 
 (*We create a list composed by strings that satisfy the following rule : they
   have the same levenshtein distance, which is the minimum distance between the
-  reference word "keyword" and all the strings in "string_list" (with the
+  reference word "keyword" and all the strings in "candidates" (with the
   condition that this minimum is equal to or less than one third of the length
   of keyword + 1, in order to get suggestions close to "keyword")*)
 let suggestion_minimum_levenshtein_distance_association
-    (string_list : string list)
+    (candidates : string list)
     (keyword : string) : string list option =
   let rec strings_minimum_levenshtein_distance
       (minimum : int)
       (result : string list)
-      (string_list' : string list) : string list =
-    (*As we iterate through the "string_list'" list, we create a list "result"
+      (candidates' : string list) : string list =
+    (*As we iterate through the "candidates'" list, we create a list "result"
       with all strings that have the last minimum levenshtein distance found
       ("minimum").*)
-    match string_list' with
+    match candidates' with
     (*When a new minimum levenshtein distance is found, the new result list is
       our new element "current_string" followed by strings that have the same
       minimum distance. It will be the "result" list if there is no levenshtein
@@ -85,7 +85,7 @@ let suggestion_minimum_levenshtein_distance_association
         (*If a levenshtein distance greater than the minimum is found, "result"
           doesn't change*)
       else strings_minimum_levenshtein_distance minimum result tail
-    (*The "result" list is returned at the end of the "string_list'" list.*)
+    (*The "result" list is returned at the end of the "candidates'" list.*)
     | [] -> result
   in
   let suggestions =
@@ -93,7 +93,7 @@ let suggestion_minimum_levenshtein_distance_association
       (1 + (String.length keyword / 3))
       (*In order to select suggestions that are not too far away from the
         keyword*)
-      [] string_list
+      [] candidates
   in
   match suggestions with [] -> None | _ :: _ -> Some suggestions
 
@@ -103,6 +103,6 @@ let display (suggestions_list : string list) (ppf : Format.formatter) =
   | _ :: _ ->
     Format.pp_print_string ppf "Maybe you wanted to write : ";
     Format.pp_print_list
-      ~pp_sep:(fun ppf () -> Format.fprintf ppf ",@,or ")
+      ~pp_sep:(fun ppf () -> Format.fprintf ppf ",@ or ")
       (fun ppf string -> Format.fprintf ppf "@{<yellow>\"%s\"@}" string)
       ppf suggestions_list

compiler/surface/parser.messages

@@ -590,7 +590,7 @@ source_file: BEGIN_CODE SCOPE UIDENT COLON RULE LIDENT YEAR
 ## LIDENT
 ##
 
-expected a condition or a consequence for this rule, or the rest of the variable qualified name
+expected 'under condition' followed by a condition, 'equals' followed by the definition body, or the rest of the variable qualified name
 
 source_file: BEGIN_CODE SCOPE UIDENT COLON RULE YEAR
 ##

compiler/surface/parser_driver.ml

@@ -131,12 +131,19 @@ module ParserAux (LocalisedLexer : Lexer_common.LocalisedLexer) = struct
     in
     (* The parser has suspended itself because of a syntax error. Stop. *)
     let custom_menhir_message ppf =
-      match Parser_errors.message (state env) with
+      (match Parser_errors.message (state env) with
       | exception Not_found ->
-        Format.fprintf ppf "Message: @{<yellow>unexpected token@}"
+        Format.fprintf ppf "Message: @{<yellow>unexpected token@}@,%t"
       | msg ->
-        Format.fprintf ppf "Message: @{<yellow>%s@}"
-          (String.trim (String.uncapitalize_ascii msg))
+        Format.fprintf ppf "Message: @{<yellow>%s@}@,%t"
+          (String.trim (String.uncapitalize_ascii msg)))
+        (fun (ppf : Format.formatter) ->
+          Format.fprintf ppf "You can only write : ";
+          Format.pp_print_list
+            ~pp_sep:(fun ppf () -> Format.fprintf ppf ",@ or ")
+            (fun ppf string -> Format.fprintf ppf "@{<yellow>\"%s\"@}" string)
+            ppf
+            (List.map (fun (s, _) -> s) acceptable_tokens))
     in
     raise_parser_error ?suggestion:similar_acceptable_tokens
       (Pos.from_lpos (lexing_positions lexbuf))

examples/NSW_community_gaming/tests/test_nsw_social_housie.catala_en

@@ -31,6 +31,8 @@ $ catala Interpret -s Test1
 [ERROR]
 Syntax error at token "scope"
 Message: expected either 'condition', or 'content' followed by the expected variable type
+You can only write : "condition",
+or "content"
 
 Error token:
 ┌─⯈ examples/NSW_community_gaming/tests/test_nsw_social_housie.catala_en:11.21-11.26:
@@ -73,6 +75,8 @@ $ catala Interpret -s Test2
 [ERROR]
 Syntax error at token "scope"
 Message: expected either 'condition', or 'content' followed by the expected variable type
+You can only write : "condition",
+or "content"
 
 Error token:
 ┌─⯈ examples/NSW_community_gaming/tests/test_nsw_social_housie.catala_en:11.21-11.26:
@@ -115,6 +119,8 @@ $ catala Interpret -s Test3
 [ERROR]
 Syntax error at token "scope"
 Message: expected either 'condition', or 'content' followed by the expected variable type
+You can only write : "condition",
+or "content"
 
 Error token:
 ┌─⯈ examples/NSW_community_gaming/tests/test_nsw_social_housie.catala_en:11.21-11.26:
@@ -159,6 +165,8 @@ $ catala Interpret -s Test4
 [ERROR]
 Syntax error at token "scope"
 Message: expected either 'condition', or 'content' followed by the expected variable type
+You can only write : "condition",
+or "content"
 
 Error token:
 ┌─⯈ examples/NSW_community_gaming/tests/test_nsw_social_housie.catala_en:11.21-11.26: