Guile Present. version 0.3.0, updated 21 September Andy Wingo

Guile Present

version 0.3.0, updated 21 September 2014

This manual is for Guile Present (version 0.3.0, updated 21 September 2014) Copyright 2014 Andy Wingo

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License or (at your option) any later version. You should have received a copy of the GNU Lesser General Public License along with this manual; if not, see http://www.gnu.org/licenses/.

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Short Contents

1 (present)

. . . .

2 (present org-mode)

. . . .

3 (present texinfo)

. . . .

4 (present cairo)

. . . .

5 (present svg)

. . . .

6 (present fold)

. . . .

7 (present util)

. . . .

8 org-to-pdf-presentation

. . . .

9 texi-to-pdf-presentation

. . . .

Concept Index

. . . .

Chapter 1: (present) 1

1 (present)

1.1 Overview

Guile-Present is a library to create presentations in Guile Scheme. It has three parts:

• A specification of the declarative presentationlanguage;

• A set of parsers to transform other formats to the presentation language; and

• A rendering library to render a presentation onto some kind of graphics device. For examples of a parser, see Chapter 2 [(present org-mode)], page 3.

Renderers are built on a pure-functional layout algorithm (seeChapter 6 [(present fold)], page 7).

One renderer (see[presentation->svg], page 6) produces a single layered SVG.

Guile-Present also includes a command line tool (seeChapter 8 [org-to-pdf-presentation], page 10) to render an Org Mode file directly into a PDF suitable for presenting with a PDF viewer.

See Section “Summary” inOrg Mode Manual, for more information on Org Mode.

1.2 Presentation language

The presentation language defined in Guile-Present is a dialect of SXML. Seehttp://ssax. sourceforge.net/ for more information on SXML.

The elements defined in the presentation language are as follows: presentation

The top-level node. No attributes defined; may contain slideelements. slide Defines a slide. May contain attributes title and level, where level is an

integer indicating the level of subsectioning.

title A title, as might appear on a title slide. May contain text elements, which will normally be rendered on a separate lines.

header A header line. May contain text elements, which will normally be rendered on a separate lines.

image An image. May not contain subelements. Will open an image named the current value of the image-filename parameter, at the size image-width and image-height.

p A set of text lines. No attributes defined. Each child text element will normally be rendered on a separate line.

ul An unordered list. May only contain lielements. No attributes defined. li A list element. May contain porul elements. No attributes defined.

For example, the following example shows a presentation with one title slide and one body slide:

Chapter 1: (present) 2

(presentation

(slide (@ (title "title-slide") (level 0)) (title "Presentation language")) (slide (@ (title "Summary") (level 1))

(header "Summary")

(p "The presentation language"

"is not particularly expressive.") (ul

(li (p "Few elements defined")

(ul (li (p "This will change with time")))) (li "Unclear specification"))

(p "However, it is what we have.")))

Chapter 2: (present org-mode) 3

2 (present org-mode)

2.1 Overview

Routines to read files written in Emacs’ org-mode, parsing them into the presentation SXML language.

2.2 Usage

[Function]

org->presentation port

Parse a file written in Emacs’ org-mode into the presentation SXML format.

Note that only a limited subset of org-mode’s syntax is understood. Specifically, inline text formatters (e.g. ‘_emphasized_’) are not parsed, although it would be nice to do so in the future.

Here is an example of a document that this code understands: # mode: org; fill-column: 34

-*-#+TITLE: Presentation title * Outline

First we talk about this Then we talk about that * This

** This: foo Whereas

* Foo is an elegant solution to problems in the bar domain * Still, baz

* Zag

* Metasyntactic Foo!

Chapter 3: (present texinfo) 4

3 (present texinfo)

3.1 Overview

Transform parsed texinfo into the presentation SXML language. See Guile-Lib’s(texinfo) for more information.

3.2 Usage

[Function]

stexi->presentation stexi

Transform stexi into the presentation SXML format. Note that only a limited subset of texinfo is understood.

Chapter 4: (present cairo) 5

4 (present cairo)

4.1 Overview

Routines to render SXML documents from the presentation vocabulary using the Cairo graphics library.

4.2 Usage

[Function]

presentation-render-cairo presentation cr

Convert an SXML document in thepresentationvocabulary to a multi-layered SVG. The result will still be a document in SXML format, so if you want to write it to disk, usesxml->xml. See Section “(sxml simple)” inGuile Library, for more information. The resulting SVG will be written with annotations readable by Inkscape, a vector graphics editor, which help to make the SVG easily editable. If your toolchain does not understand namespaces, you might want to filter out elements that start with ‘sodipodi:’, ‘xmlns:’, and ‘inkscape:’.

Chapter 5: (present svg) 6

5 (present svg)

5.1 Overview

Routines to transform SXML documents from the presentation vocabulary into SVG. The code in this file was originally presented in Andy Wingo’s 2007 paper,Applications of fold to XML transformation.

5.2 Usage

[Function]

presentation->svg presentation

Convert an SXML document in thepresentationvocabulary to a multi-layered SVG. The result will still be a document in SXML format, so if you want to write it to disk, usesxml->xml. See Section “(sxml simple)” inGuile Library, for more information. The resulting SVG will be written with annotations readable by Inkscape, a vector graphics editor, which help to make the SVG easily editable. If your toolchain does not understand namespaces, you might want to filter out elements that start with ‘sodipodi:’, ‘xmlns:’, and ‘inkscape:’.

Chapter 6: (present fold) 7

6 (present fold)

6.1 Overview

(present fold) defines a number of variants of thefold algorithm for use in transforming presentations. Additionally it defines the layout operator, fold-layout, which might be described as a context-passing variant of SSAX’spre-post-order.

6.2 Usage

[Function]

foldt fup fhere tree

The standard multithreaded tree fold.

fup is of type [a] ->a. fhere is of type object ->a.

[Function]

fold proc seed list

The standard list fold.

proc is of type a ->b ->b. seed is of type b. list is of type [a].

[Function]

foldts fdown fup fhere seed tree

The single-threaded tree fold originally defined in SSAX. See Section “(sxml ssax)” inGuile Library, for more information.

[Function]

foldts* fdown fup fhere seed tree

A variant of [foldts], page 7that allows pre-order tree rewrites. Originally defined in Andy Wingo’s 2007 paper, Applications of fold to XML transformation.

[Function]

fold-values proc list . seeds

A variant of[fold], page 7 that allows multi-valued seeds. Note that the order of the arguments differs from that offold.

[Function]

foldts*-values fdown fup fhere tree . seeds

A variant of [foldts*], page 7 that allows multi-valued seeds. Originally defined in Andy Wingo’s 2007 paper, Applications of fold to XML transformation.

[Function]

fold-layout tree bindings params layout stylesheet

A traversal combinator in the spirit of SSAX’s Section “pre-post-order” in Guile Library.

fold-layout was originally presented in Andy Wingo’s 2007 paper,Applications of fold to XML transformation.

bindings := (<binding>...)

binding := (<tag> <handler-pair>...) | (*default* <handler-pair> ...) | (*text* . <text-handler>) tag := <symbol>

handler-pair := (pre-layout . <pre-layout-handler>) | (post . <post-handler>)

| (bindings . <bindings>) | (pre . <pre-handler>) | (macro . <macro-handler>)

Chapter 6: (present fold) 8

pre-layout-handler

A function of three arguments:

kids the kids of the current node, before traversal params the params of the current node

layout the layout coming into this node

pre-layout-handler is expected to use this information to return a layout to pass to the kids. The default implementation returns the layout given in the arguments.

post-handler

A function of five arguments:

tag the current tag being processed params the params of the current node

layout the layout coming into the current node, before any kids were processed

klayout the layout after processing all of the children kids the already-processed child nodes

post-handler should return two values, the layout to pass to the next node and the final tree.

text-handler

text-handler is a function of three arguments: text the string

params the current params layout the current layout

text-handlershould return two values, the layout to pass to the next node and the value to which the string should transform.

Chapter 7: (present util) 9

7 (present util)

7.1 Overview

Utility procedures and macros.

7.2 Usage

[Special Form]

match-bind

Match a string against a regular expression, binding lexical variables to the various parts of the match.

vars is a list of names to which to bind the parts of the match. The first variable of the list will be bound to the entire match, so the number of variables needed will be equal to the number of open parentheses (‘(’) in the pattern, plus one for the whole match.

consequent is executed if the given expression str matches regex. If the string does not match,alternatewill be executed if present. Ifalternateis not present, the result of match-bindis unspecified.

Here is a short example:

(define (star-indent line)

"Returns the number of spaces until the first star (‘*’) in the input, or #f if the first non-space character is not a star."

(match-bind "^( *)\*.*$" line (_ spaces) (string-length spaces)

#f))

match-bindcompiles the regular expressionregex at macro expansion time. For this reason, regex must be a string literal, not an arbitrary expression.

Chapter 8: org-to-pdf-presentation 10

8 org-to-pdf-presentation

8.1 Overview

org-to-pdf-presentation is a command-line script offered by Guile-Lib that can trans-form a file written in Emacs’ Org Mode and directly produce a PDF file, suitable for presenting with a PDF viewer.

org-to-pdf-presentation works by rendering each slide as an SVG, then using librsvg to convert the SVGs to one PDF of many pages. You will need the tool, rsvg-convert, provided under Debian as librsvg2-bin.

8.2 Usage

[Command]

org-to-pdf-presentation in-org-file out-pdf-file

Convert the Org Mode filein-org-file into a PDF suitable for presentations.

This command is subject to the limitations of org->presentation. Namely, only a subset of all Org Mode constructs are supported. See[org->presentation], page 3, for more information.

Chapter 9: texi-to-pdf-presentation 11

9 texi-to-pdf-presentation

9.1 Overview

texi-to-pdf-presentation is a command-line script offered by Guile-Present that can transform a file written in a subset of Texinfo into a presentation as a PDF file, suitable for presenting with a PDF viewer.

texi-to-pdf-presentation works by rendering each slide using Guile-Cairo. You will need Guile-Cairo, and optionally guile-rsvg if you include SVG images.

9.2 Usage

[Command]

texi-to-pdf-presentation in-texi-file out-pdf-file

Convert the Texinfo file in-texi-file into a PDF suitable for presentations.

This command is subject to the limitations of stexi->presentation. Namely, only a subset of all Texinfo constructs are supported. See[stexi->presentation], page 4, for more information.

Concept Index 12

Concept Index

Function Index 13

Function Index

F

fold. . . 7

fold-layout. . . 7

fold-values. . . 7

foldt. . . 7

foldts. . . 7

foldts*. . . 7

foldts*-values. . . 7

M

O

org-to-pdf-presentation. . . 10

P

presentation-render-cairo. . . 5

S

T