graphviz-2999.20.0.2: Bindings to Graphviz for graph visualisation.

Copyright(c) Ivan Lazar Miljenovic
License3-Clause BSD-style
Safe HaskellNone




Four different representations of Dot graphs are available, all of which are based loosely upon the specifications at: The DotRepr class provides a common interface for them (the PrintDotRepr, ParseDotRepr and PPDotRepr classes are used until class aliases are implemented).

Every representation takes in a type parameter: this indicates the node type (e.g. DotGraph Int is a Dot graph with integer nodes). Sum types are allowed, though care must be taken when specifying their ParseDot instances if there is the possibility of overlapping definitions. The GraphID type is an existing sum type that allows textual and numeric values.

If you require using more than one Dot representation, you will most likely need to import at least one of them qualified, as they typically all use the same names.

As a comparison, all four representations provide how you would define the following Dot graph (or at least one isomorphic to it) (the original of which can be found at Note that in all the examples, they are not necessarily done the best way (variables rather than repeated constants, etc.); they are just there to provide a comparison on the structure of each representation.

digraph G {

  subgraph cluster_0 {
    node [style=filled,color=white];
    a0 -> a1 -> a2 -> a3;
    label = "process #1";

  subgraph cluster_1 {
    node [style=filled];
    b0 -> b1 -> b2 -> b3;
    label = "process #2";
  start -> a0;
  start -> b0;
  a1 -> b3;
  b2 -> a3;
  a3 -> a0;
  a3 -> end;
  b3 -> end;

  start [shape=Mdiamond];
  end [shape=Msquare];

Each representation is suited for different things:

is ideal for converting other graph-like data structures into Dot graphs (the Data.GraphViz module provides some functions for this). It is a structured representation of Dot code.
matches the actual structure of Dot code. As such, it is suited for parsing in existing Dot code.
provides graph operations for manipulating Dot graphs; this is suited when you want to edit existing Dot code. It uses generalised Dot graphs for parsing and canonical Dot graphs for printing.
is a much easier representation to use when defining relatively static Dot graphs in Haskell code, and looks vaguely like actual Dot code if you squint a bit.

Please also read the limitations section at the end for advice on how to properly use these Dot representations.



class Ord n => DotRepr dg n where Source #

This class is used to provide a common interface to different ways of representing a graph in Dot form.

You will most probably not need to create your own instances of this class.

The type variable represents the current node type of the Dot graph, and the Ord restriction is there because in practice most implementations of some of these methods require it.


fromCanonical :: DotGraph n -> dg n Source #

Convert from a graph in canonical form. This is especially useful when using the functions from Data.GraphViz.Algorithms.

See FromGeneralisedDot in Data.GraphViz.Types.Generalised for a semi-inverse of this function.

getID :: dg n -> Maybe GraphID Source #

Return the ID of the graph.

setID :: GraphID -> dg n -> dg n Source #

Set the ID of the graph.

graphIsDirected :: dg n -> Bool Source #

Is this graph directed?

setIsDirected :: Bool -> dg n -> dg n Source #

Set whether a graph is directed or not.

graphIsStrict :: dg n -> Bool Source #

Is this graph strict? Strict graphs disallow multiple edges.

setStrictness :: Bool -> dg n -> dg n Source #

A strict graph disallows multiple edges.

mapDotGraph :: DotRepr dg n' => (n -> n') -> dg n -> dg n' Source #

Change the node values. This function is assumed to be injective, otherwise the resulting graph will not be identical to the original (modulo labels).

graphStructureInformation :: dg n -> (GlobalAttributes, ClusterLookup) Source #

Return information on all the clusters contained within this DotRepr, as well as the top-level GraphAttrs for the overall graph.

nodeInformation :: Bool -> dg n -> NodeLookup n Source #

Return information on the DotNodes contained within this DotRepr. The Bool parameter indicates if applicable NodeAttrs should be included.

edgeInformation :: Bool -> dg n -> [DotEdge n] Source #

Return information on the DotEdges contained within this DotRepr. The Bool parameter indicates if applicable EdgeAttrs should be included.

unAnonymise :: dg n -> dg n Source #

Give any anonymous sub-graphs or clusters a unique identifier (i.e. there will be no Nothing key in the ClusterLookup from graphStructureInformation).


Ord n => DotRepr DotGraph n Source # 
Ord n => DotRepr DotGraph n Source # 
Ord n => DotRepr DotGraph n Source # 

class PrintDot a where Source #

A class used to correctly print parts of the Graphviz Dot language. Minimal implementation is unqtDot.

Minimal complete definition



unqtDot :: a -> DotCode Source #

The unquoted representation, for use when composing values to produce a larger printing value.

toDot :: a -> DotCode Source #

The actual quoted representation; this should be quoted if it contains characters not permitted a plain ID String, a number or it is not an HTML string. Defaults to unqtDot.

unqtListToDot :: [a] -> DotCode Source #

The correct way of representing a list of this value when printed; not all Dot values require this to be implemented. Defaults to Haskell-like list representation.

listToDot :: [a] -> DotCode Source #

The quoted form of unqtListToDot; defaults to wrapping double quotes around the result of unqtListToDot (since the default implementation has characters that must be quoted).


PrintDot Bool Source # 
PrintDot Char Source # 
PrintDot Double Source # 
PrintDot Int Source # 
PrintDot Integer Source # 
PrintDot Word8 Source # 
PrintDot Word16 Source # 
PrintDot Version Source #

Ignores versionTags and assumes 'not . null . versionBranch' (usually you want 'length . versionBranch == 2').

PrintDot Text Source # 
PrintDot Text Source # 
PrintDot BrewerName Source # 
PrintDot BrewerScheme Source # 
PrintDot ColorScheme Source # 
PrintDot GraphvizCommand Source # 
PrintDot CompassPoint Source # 
PrintDot PortPos Source # 
PrintDot PortName Source # 
PrintDot X11Color Source # 
PrintDot SVGColor Source # 
PrintDot WeightedColor Source # 
PrintDot Color Source # 
PrintDot Style Source # 
PrintDot Side Source # 
PrintDot Scale Source # 
PrintDot CellFormat Source # 
PrintDot VAlign Source # 
PrintDot Align Source # 
PrintDot Attribute Source # 
PrintDot Img Source # 
PrintDot Cell Source # 
PrintDot Row Source # 
PrintDot Table Source # 
PrintDot Format Source # 
PrintDot TextItem Source # 
PrintDot Label Source # 
PrintDot NodeSize Source # 
PrintDot Normalized Source # 
PrintDot Number Source # 
PrintDot Ratios Source # 
PrintDot Justification Source # 
PrintDot ScaleType Source # 
PrintDot Paths Source # 
PrintDot VerticalPlacement Source # 
PrintDot FocusType Source # 
PrintDot ViewPort Source # 
PrintDot StyleName Source # 
PrintDot StyleItem Source # 
PrintDot STStyle Source # 
PrintDot StartType Source # 
PrintDot SmoothType Source # 
PrintDot Shape Source # 
PrintDot RankDir Source # 
PrintDot RankType Source # 
PrintDot Root Source # 
PrintDot QuadType Source # 
PrintDot Spline Source # 
PrintDot PageDir Source # 
PrintDot EdgeType Source # 
PrintDot Pos Source # 
PrintDot PackMode Source # 
PrintDot Pack Source # 
PrintDot OutputMode Source # 
PrintDot Order Source # 
PrintDot LayerList Source # 
PrintDot LayerID Source # 
PrintDot LayerRangeElem Source # 
PrintDot LayerListSep Source # 
PrintDot LayerSep Source # 
PrintDot Overlap Source # 
PrintDot Point Source # 
PrintDot LabelScheme Source # 
PrintDot RecordField Source # 
PrintDot Label Source # 
PrintDot Model Source # 
PrintDot ModeType Source # 
PrintDot GraphSize Source # 
PrintDot SVGFontNames Source # 
PrintDot DPoint Source # 
PrintDot DEConstraints Source # 
PrintDot DirType Source # 
PrintDot ClusterMode Source # 
PrintDot Rect Source # 
PrintDot ArrowSide Source # 
PrintDot ArrowFill Source # 
PrintDot ArrowModifier Source # 
PrintDot ArrowShape Source # 
PrintDot ArrowType Source # 
PrintDot Attribute Source # 
PrintDot GlobalAttributes Source # 
PrintDot GraphID Source # 
PrintDot a => PrintDot [a] Source # 


unqtDot :: [a] -> DotCode Source #

toDot :: [a] -> DotCode Source #

unqtListToDot :: [[a]] -> DotCode Source #

listToDot :: [[a]] -> DotCode Source #

PrintDot n => PrintDot (DotEdge n) Source # 
PrintDot n => PrintDot (DotNode n) Source # 
PrintDot n => PrintDot (DotSubGraph n) Source # 
PrintDot n => PrintDot (DotStatements n) Source # 
PrintDot n => PrintDot (DotGraph n) Source # 
PrintDot n => PrintDot (DotSubGraph n) Source # 
PrintDot n => PrintDot (DotStatement n) Source # 
PrintDot n => PrintDot (DotGraph n) Source # 
PrintDot n => PrintDot (DotGraph n) Source #

Uses the PrintDot instance for canonical DotGraphs.

class ParseDot a where Source #

Minimal complete definition



ParseDot Bool Source # 
ParseDot Char Source # 
ParseDot Double Source # 
ParseDot Int Source # 
ParseDot Integer Source # 
ParseDot Word8 Source # 
ParseDot Word16 Source # 
ParseDot Version Source #

Ignores versionTags and assumes 'not . null . versionBranch' (usually you want 'length . versionBranch == 2') and that all such values are non-negative.

ParseDot Text Source # 
ParseDot Text Source # 
ParseDot BrewerName Source # 
ParseDot BrewerScheme Source # 
ParseDot ColorScheme Source # 
ParseDot GraphvizCommand Source # 
ParseDot CompassPoint Source # 
ParseDot PortPos Source # 
ParseDot PortName Source # 
ParseDot X11Color Source # 
ParseDot SVGColor Source # 
ParseDot WeightedColor Source # 
ParseDot Color Source # 
ParseDot Style Source # 
ParseDot Side Source # 
ParseDot Scale Source # 
ParseDot CellFormat Source # 
ParseDot VAlign Source # 
ParseDot Align Source # 
ParseDot Attribute Source # 
ParseDot Img Source # 
ParseDot Cell Source # 
ParseDot Row Source # 
ParseDot Table Source # 
ParseDot Format Source # 
ParseDot TextItem Source # 
ParseDot Label Source # 
ParseDot NodeSize Source # 
ParseDot Normalized Source # 
ParseDot Number Source # 
ParseDot Ratios Source # 
ParseDot Justification Source # 
ParseDot ScaleType Source # 
ParseDot Paths Source # 
ParseDot VerticalPlacement Source # 
ParseDot FocusType Source # 
ParseDot ViewPort Source # 
ParseDot StyleName Source # 
ParseDot StyleItem Source # 
ParseDot STStyle Source # 
ParseDot StartType Source # 
ParseDot SmoothType Source # 
ParseDot Shape Source # 
ParseDot RankDir Source # 
ParseDot RankType Source # 
ParseDot Root Source # 
ParseDot QuadType Source # 
ParseDot Spline Source # 
ParseDot PageDir Source # 
ParseDot EdgeType Source # 
ParseDot Pos Source # 
ParseDot PackMode Source # 
ParseDot Pack Source # 
ParseDot OutputMode Source # 
ParseDot Order Source # 
ParseDot LayerList Source # 
ParseDot LayerID Source # 
ParseDot LayerRangeElem Source # 
ParseDot LayerListSep Source # 
ParseDot LayerSep Source # 
ParseDot Overlap Source #

Note that overlap=false defaults to PrismOverlap Nothing, but if the Prism library isn't available then it is equivalent to VoronoiOverlap.

ParseDot Point Source # 
ParseDot LabelScheme Source # 
ParseDot RecordField Source # 
ParseDot Label Source # 
ParseDot Model Source # 
ParseDot ModeType Source # 
ParseDot GraphSize Source # 
ParseDot SVGFontNames Source # 
ParseDot DPoint Source # 
ParseDot DEConstraints Source # 
ParseDot DirType Source # 
ParseDot ClusterMode Source # 
ParseDot Rect Source # 
ParseDot ArrowSide Source # 
ParseDot ArrowFill Source # 
ParseDot ArrowModifier Source # 
ParseDot ArrowShape Source # 
ParseDot ArrowType Source # 
ParseDot Attribute Source # 
ParseDot GlobalAttributes Source # 
ParseDot GraphID Source # 
ParseDot a => ParseDot [a] Source # 
ParseDot n => ParseDot (DotEdge n) Source # 
ParseDot n => ParseDot (DotNode n) Source # 
ParseDot n => ParseDot (DotSubGraph n) Source # 
ParseDot n => ParseDot (DotStatements n) Source # 
ParseDot n => ParseDot (DotGraph n) Source # 
ParseDot n => ParseDot (DotSubGraph n) Source # 
ParseDot n => ParseDot (DotStatement n) Source # 
ParseDot n => ParseDot (DotGraph n) Source # 
(Ord n, ParseDot n) => ParseDot (DotGraph n) Source #

Uses the ParseDot instance for generalised DotGraphs.

class (DotRepr dg n, PrintDot (dg n)) => PrintDotRepr dg n Source #

This class exists just to make type signatures nicer; all instances of DotRepr should also be an instance of PrintDotRepr.

class (DotRepr dg n, ParseDot (dg n)) => ParseDotRepr dg n Source #

This class exists just to make type signatures nicer; all instances of DotRepr should also be an instance of ParseDotRepr.

class (PrintDotRepr dg n, ParseDotRepr dg n) => PPDotRepr dg n Source #

This class exists just to make type signatures nicer; all instances of DotRepr should also be an instance of PPDotRepr.

Common sub-types

data GraphID Source #

A polymorphic type that covers all possible ID values allowed by Dot syntax. Note that whilst the ParseDot and PrintDot instances for String will properly take care of the special cases for numbers, they are treated differently here.


Str Text 
Num Number 

class ToGraphID a where Source #

A convenience class to make it easier to convert data types to GraphID values, e.g. for cluster identifiers.

In most cases, conversion would be via the Text or String instances (e.g. using show).

Minimal complete definition



toGraphID :: a -> GraphID Source #

textGraphID :: Text -> GraphID Source #

An alias for toGraphID for use with the OverloadedStrings extension.

data GlobalAttributes Source #

Represents a list of top-level list of Attributes for the entire graph/sub-graph. Note that GraphAttrs also applies to DotSubGraphs.

Note that Dot allows a single Attribute to be listed on a line; if this is the case then when parsing, the type of Attribute it is determined and that type of GlobalAttribute is created.








data DotNode n Source #

A node in DotGraph.



data DotEdge n Source #

An edge in DotGraph.




Helper types for looking up information within a DotRepr.

type ClusterLookup = Map (Maybe GraphID) ([Path], GlobalAttributes) Source #

The available information for each cluster; the [Path] denotes all locations where that particular cluster is located (more than one location can indicate possible problems).

type NodeLookup n = Map n (Path, Attributes) Source #

The available information on each DotNode (both explicit and implicit).

type Path = Seq (Maybe GraphID) Source #

The path of clusters that must be traversed to reach this spot.

graphStructureInformationClean :: DotRepr dg n => dg n -> (GlobalAttributes, ClusterLookup) Source #

A variant of graphStructureInformation with default attributes removed and only attributes usable by graph/cluster kept (where applicable).

nodeInformationClean :: DotRepr dg n => Bool -> dg n -> NodeLookup n Source #

A variant of nodeInformation with default attributes removed and only attributes used by nodes kept.

edgeInformationClean :: DotRepr dg n => Bool -> dg n -> [DotEdge n] Source #

A variant of edgeInformation with default attributes removed and only attributes used by edges kept.

Obtaining the DotNodes and DotEdges.

graphNodes :: DotRepr dg n => dg n -> [DotNode n] Source #

Returns all resultant DotNodes in the DotRepr (not including NodeAttrs).

graphEdges :: DotRepr dg n => dg n -> [DotEdge n] Source #

Returns all resultant DotEdges in the DotRepr (not including EdgeAttrs).

Printing and parsing a DotRepr.

printDotGraph :: PrintDotRepr dg n => dg n -> Text Source #

The actual Dot code for an instance of DotRepr. Note that it is expected that parseDotGraph . printDotGraph == id (this might not be true the other way around due to un-parseable components).

parseDotGraph :: ParseDotRepr dg n => Text -> dg n Source #

Parse a limited subset of the Dot language to form an instance of DotRepr. Each instance may have its own limitations on what may or may not be parseable Dot code.

Also removes any comments, etc. before parsing.

parseDotGraphLiberally :: ParseDotRepr dg n => Text -> dg n Source #

As with parseDotGraph, but if an Attribute cannot be parsed strictly according to the known rules, let it fall back to being parsed as an UnknownAttribute. This is especially useful for when using a version of Graphviz that is either newer (especially for the XDot attributes) or older (when some attributes have changed) but you'd still prefer it to parse rather than throwing an error.

Limitations and documentation

Printing of Dot code is done as strictly as possible, whilst parsing is as permissive as possible. For example, if the types allow it then "2" will be parsed as an Int value. Note that quoting and escaping of textual values is done automagically.

A summary of known limitations/differences:

  • When creating GraphID values for graphs and sub-graphs, you should ensure that none of them have the same printed value as one of the node identifiers values to avoid any possible problems.
  • If you want any GlobalAttributes in a sub-graph and want them to only apply to that sub-graph, then you must ensure it does indeed have a valid GraphID.
  • All sub-graphs which represent clusters should have unique identifiers (well, only if you want them to be generated sensibly).
  • If eventually outputting to a format such as SVG, then you should make sure to specify an identifier for the overall graph, as that is used as the title of the resulting image.
  • Whilst the graphs, etc. are polymorphic in their node type, you should ensure that you use a relatively simple node type (that is, it only covers a single line, etc.).
  • Also, whilst Graphviz allows you to mix the types used for nodes, this library requires/assumes that they are all the same type (but you can use a sum-type).
  • DotEdge defines an edge (a, b) (with an edge going from a to b); in Dot parlance the edge has a head at a and a tail at b. Care must be taken when using the related Head* and Tail* Attributes. See the differences section in Data.GraphViz.Attributes for more information.
  • It is common to see multiple edges defined on the one line in Dot (e.g. n1 -> n2 -> n3 means to create a directed edge from n1 to n2 and from n2 to n3). These types of edge definitions are parseable; however, they are converted to singleton edges.
  • It is not yet possible to create or parse edges with subgraphs/clusters as one of the end points.
  • The parser will strip out comments and pre-processor lines, join together multiline statements and concatenate split strings together. However, pre-processing within HTML-like labels is currently not supported.
  • Graphviz allows a node to be "defined" twice (e.g. the actual node definition, and then in a subgraph with extra global attributes applied to it). This actually represents the same node, but when parsing they will be considered as separate DotNodes (such that graphNodes will return both "definitions"). canonicalise from Data.GraphViz.Algorithms can be used to fix this.

See Data.GraphViz.Attributes.Complete for more limitations.