elm-parser-error-extra

This package allows to pretty print errors coming from Parser.run.

You will need a function which is specific to your output kind, be it the console, Html or Markdown. Those are presented below and not included in the package to keep the dependency list minimal.

Colored console output

Depends on wolfadex/elm-ansi.

errorToString :
    String
    -> List (DeadEnd inner problem)
    -> String
errorToString src deadEnds =
    renderError
        { text = identity
        , colorContext = Ansi.Color.fontColor Ansi.Color.cyan
        , colorCaret = Ansi.Color.fontColor Ansi.Color.red
        , newline = "\n"
        , context = 3
        }
        Parser.Error.forParser -- or Parser.Error.forParserAdvanced
        src
        deadEnds
        |> String.concat

Markdown

Depends on dillonkearns/elm-markdown.

errorToMarkdown :
    String
    -> List (DeadEnd inner problem)
    -> Block
errorToMarkdown src deadEnds =
    let
        color : String -> Inline -> Inline
        color value child =
            Block.HtmlInline
                (Block.HtmlElement "span"
                    [ { name = "style", value = "color:" ++ value } ]
                    [ Block.Paragraph [ child ] ]
                )
    in
    renderError
        { text = Block.CodeSpan
        , colorContext = color "cyan"
        , colorCaret = color "red"
        , newline = Block.HardLineBreak
        , context = 3
        }
        Parser.Error.forParser -- or Parser.Error.forParserAdvanced
        src
        deadEnds
        |> Block.Paragraph

Html

Depends on elm/html.

errorToHtml :
    String
    -> List (DeadEnd inner Problem)
    -> Html msg
errorToHtml src deadEnds =
    let
        color : String -> Html msg -> Html msg
        color value child =
            Html.span [ Html.Attributes.style "color" value ] [ child ]
    in
    renderError
        { text = Html.text
        , colorContext = color "cyan"
        , colorCaret = color "red"
        , newline = Html.br [] []
        , context = 3
        }
        Parser.Error.forParser -- or Parser.Error.forParserAdvanced
        src
        deadEnds
        |> Html.pre []