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diff --git a/README.md b/README.md new file mode 100644 index 0000000..0f030a8 --- /dev/null +++ b/README.md @@ -0,0 +1,98 @@ +# About chains + +Chains is a Lisp inspired programming language designed to serve as a +preprocessor replacement. Just as Lisp stands for List Processing, Chains is in +a sense Tree Processing. It was originaly designed with the generation of HTML +in mind, but it does not restrict itself to this task. + +The result of evaluating a program is a tree, which may then be used to generate +other markup languages. However, chains is not a macro language like the +C preprocessor or m4. + +One of the issues of generating markup text from within a conventional +programming language is how cumbersome this is. Due to the syntax rules of the +language, the markup must be in a way escaped e.g. by writing a string between +quotes. Meanwhile unquoted items are syntactic elements of the language. This +way writing code is "easy" while writing markup is "cumbersome". + +In Chains, text is a first class citizen and all other syntactic elements have +to be escaped. Because of this, you probably won't want to write Chains code +directly but instead define it inside of the interpreter. On the other hand, +writing markup is as easy as writing markdown or TeX. + +The language also has a built-in notion of paragraph + +At the moment, chains is more a proof of concept rather than a complete +language. Many features are still undecided. + +# Syntax + +| Character | Description | +|-----------|-------------------------------------------------------------------------| +| % | | +| \\ | | +| { } | | +| \[ \] | | +| # | Raw function. All special characters in the arguments are taken literal | +| @ | | +| $ | | + +## Primitives +Chains is built on 3 type of objects: text, chains and atoms. + +## Evaluation rules + +Unless a chain is escaped, the following rules apply. The chain to be evaluated +may only have a single object inside the first link. The function is value of +evaluating this first element. + +Text evaluates to itself. + +Atoms consists of symbols or numbers. Symbols evaluate to the bound value in the +environment. Numbers evaluate to themselves. + +# How to contribute + +If you would like to contibute to the development of chains please send a mail +with your patch to the following address: thomas _at_ thomaslabs _dot_ org + +# Misc + +;; next-token : cache raw block for further reads. avoid creating list (1 pass) +;; build link directly instead of returning block start tokens + +;; read link +;; {} link := list of objects +;; { }{ }{ } chain := list of links +;; + +;; special form : does not get its arguments pre-evaluated + +;; after eval, unevaluated links are spliced into tree +;; {@if}{{@=}{2}{2}}{1}{2} -> {1} ;; needs to return link, in case text is also inside +;; @if{@={@2}{@2}}{1}{2} ;; alias syntax + + +;; use chains as library for static website generator, define-syntax and define +;; to define "callbacks" from library and read/eval file + +;; tree from file may be discarded ;; writing libraries + +;; a chain is evaluated by first evaluating the first link and applying the +;; other links as arguments for the function + +;; a link with one element is evaluated to that element + +;; inside the evaluation of a lambda, the argument is spliced into the link of +;; the body + +;; {{@lambda}{@x @y}{@x}}{Hello}{World} -> {{Hello}} -> {Hello} -> Hello + +;; Metaprogramming is hard :( + +;; make closure return links instead of plain lists? dont use flatten? + +;; type 1 - {{@lambda}{{@x}{@y}}{@x}}{Hello}{World} +;; type 2 - {{@lambda}{@x @y}{@x}}{Hello}{World} + +;; semantically. What exactly is a chain? |