Copyright | (c) Andrey Mokhov 2016-2019 |
---|---|
License | MIT (see the file LICENSE) |
Maintainer | andrey.mokhov@gmail.com |
Stability | experimental |
Safe Haskell | None |
Language | Haskell2010 |
Alga is a library for algebraic construction and manipulation of graphs in Haskell. See this paper for the motivation behind the library, the underlying theory, and implementation details.
This module defines basic functionality for exporting graphs in textual and binary formats. Algebra.Graph.Export.Dot provides DOT-specific functions.
Synopsis
- data Doc s
- isEmpty :: Doc s -> Bool
- literal :: s -> Doc s
- render :: Monoid s => Doc s -> s
- (<+>) :: IsString s => Doc s -> Doc s -> Doc s
- brackets :: IsString s => Doc s -> Doc s
- doubleQuotes :: IsString s => Doc s -> Doc s
- indent :: IsString s => Int -> Doc s -> Doc s
- unlines :: IsString s => [Doc s] -> Doc s
- export :: (Ord a, ToGraph g, ToVertex g ~ a) => (a -> Doc s) -> (a -> a -> Doc s) -> g -> Doc s
Constructing and exporting documents
An abstract document data type with O(1) time concatenation (the current
implementation uses difference lists). Here s
is the type of abstract
symbols or strings (text or binary). Doc
s
is a Monoid
, therefore
mempty
corresponds to the empty document and two documents can be
concatenated with mappend
(or operator <>
). Documents
comprising a single symbol or string can be constructed using the function
literal
. Alternatively, you can construct documents as string literals,
e.g. simply as "alga"
, by using the OverloadedStrings
GHC extension. To
extract the document contents use the function render
.
Note that the document comprising a single empty string is considered to be
different from the empty document. This design choice is motivated by the
desire to support string types s
that have no Eq
instance, such as
Data.ByteString.Builder, for which there is no way to check whether a
string is empty or not. As a consequence, the Eq
and Ord
instances are
defined as follows:
mempty
/=literal
""mempty
<literal
""
Instances
(Monoid s, Eq s) => Eq (Doc s) Source # | |
(Monoid s, Ord s) => Ord (Doc s) Source # | The empty document is smallest. |
(Monoid s, Show s) => Show (Doc s) Source # | |
IsString s => IsString (Doc s) Source # | |
Defined in Algebra.Graph.Export fromString :: String -> Doc s # | |
Semigroup (Doc s) Source # | |
Monoid (Doc s) Source # | |
isEmpty :: Doc s -> Bool Source #
Check if a document is empty. The result is the same as when comparing the
given document to mempty
, but this function does not require the Eq
s
constraint. Note that the document comprising a single empty string is
considered to be different from the empty document.
isEmptymempty
== True isEmpty (literal
"") == False isEmpty x == (x ==mempty
)
literal :: s -> Doc s Source #
Construct a document comprising a single symbol or string. If s
is an
instance of class IsString
, then documents of type Doc
s
can be
constructed directly from string literals (see the second example below).
literal "Hello, "<>
literal "World!" == literal "Hello, World!" literal "I am just a string literal" == "I am just a string literal"render
. literal ==id
Common combinators for text documents
brackets :: IsString s => Doc s -> Doc s Source #
Wrap a document in square brackets.
brackets "i" == "[i]"
brackets mempty
== "[]"
doubleQuotes :: IsString s => Doc s -> Doc s Source #
Wrap a document into double quotes.
doubleQuotes "/path/with spaces" == "\"/path/with spaces\""
doubleQuotes (doubleQuotes mempty
) == "\"\"\"\""
Generic graph export
export :: (Ord a, ToGraph g, ToVertex g ~ a) => (a -> Doc s) -> (a -> a -> Doc s) -> g -> Doc s Source #
Export a graph into a document given two functions that construct documents
for individual vertices and edges. The order of export is: vertices, sorted
by Ord
a
, and then edges, sorted by Ord
(a, a)
.
For example:
vDoc x =literal
(show
x) <> "\n" eDoc x y =literal
(show
x) <> " -> " <>literal
(show
y) <> "\n" > putStrLn $render
$ export vDoc eDoc (1 + 2 * (3 + 4) ::Graph
Int) 1 2 3 4 2 -> 3 2 -> 4