wumpus-core-0.37.0: Pure Haskell PostScript and SVG generation.




Extended character code handling.

Wumpus uses SVG style escaping to embed character codes or names in regular strings:

 "regular ascii text &#egrave; more ascii text"

i.e. character names and codes are delimited by &# on the left and ; on the right.

In Wumpus both character names and character codes can be embedded in strings - (e.g. &#egrave; or è ).

Character codes can be also be expressed as octal or hexadecimal:


In the generated PostScript, Wumpus uses the character name, e.g.:

 (myst) show /egrave glyphshow (re) show

The generated SVG uses the numeric code, e.g.:


To accommodate both, Wumpus defines a TextEncoder record which provides a two-way mapping between character codes and glyph names for a character set.



newtype FontEncoderName Source

Font encoder name - a newtype wrapped number.

Ideally this would be an enumerated type, but it has to be open - new encoders need to be added, so an enum is out of the question.

A String would be good, but would have slow lookup when used as a key. Dealing with multiple encoders was added late to Wumpus-Core - it is necessary, but taking a performace hit because of it is chagrin. So instead uniquely asssigned numbers are used.

Numbers below 10000 are reserved for Wumpus, though it is unlikely to need more than a handful. Numbers above are free to use (clearly clashes are possible, but probably unlikely).

Wumpus-Core assigns the following, other Wumpus libraries may assign more:

 0 - Latin1 (for Helvetica, Times Roman, Courier...)
 1 - Symbol Font



data TextEncoder Source


An instance needs:

  • A map of FontEncoderNames to FontEncoders.
  • The name of the encoding - this is printed in the xml prologue of the SVG file as the encoding attribute. Latin 1's official name is seemingly "ISO-8859-1".
  • The name of the default encoder - this should naturally be in the Font Encoder map.

data FontEncoder Source


  • The functions for looking up codes by glyph-name and glyph-name by code.
  • Fallback glyph-names and char codes in case lookup fails.

Wumpus.Core.TextLatin1 defines an implementation for Latin 1.