diff options
| author | Přemysl Janouch <p.janouch@gmail.com> | 2017-05-06 14:12:46 +0200 |
|---|---|---|
| committer | Přemysl Janouch <p.janouch@gmail.com> | 2017-05-21 13:19:44 +0200 |
| commit | a5f00256b0205e9ac6c8a5a53d5ff492adbedc5b (patch) | |
| tree | b9ba661d81f60493558cfedd00211c70b291ee0a /README.adoc | |
| parent | 75ff8091aa7746f0ff235572ea098cb083d6500a (diff) | |
| download | ell-a5f00256b0205e9ac6c8a5a53d5ff492adbedc5b.tar.gz ell-a5f00256b0205e9ac6c8a5a53d5ff492adbedc5b.tar.xz ell-a5f00256b0205e9ac6c8a5a53d5ff492adbedc5b.zip | |
Make this look like a project
Diffstat (limited to 'README.adoc')
| -rw-r--r-- | README.adoc | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/README.adoc b/README.adoc new file mode 100644 index 0000000..6206715 --- /dev/null +++ b/README.adoc @@ -0,0 +1,95 @@ +ell +=== +:compact-option: + +'ell' is a modified subset of Scheme with added syntax sugar, incorporating +ideas from Perl, Tcl and Bourne shell. The goal was to conceive a programming +language implementable with as little code as possible while still being +reasonably comfortable to use. + +This package is an implementation of said language, meant to be self-contained, +portable and reusable. Performance is specifically not an intent. + +Syntax +------ +Owing to its Scheme heritage, 'ell' is homoiconic, that is a program can be +directly expressed using the language's data types. There are only two of +those: the list and the string. Any numerical conversions are made on an +as-needed basis. Similarly, strings act like atoms/symbols when executed. + +The parser, however, does a bunch of transformations: + + * `[a b c]` makes a call to `(list a b c)`; + * `@var` is a shorthand for `(set var)`; + * `{ code }` is the most complex one. Each line within the curly braces is + wrapped in parentheses, and the resulting list is quoted, so that it doesn't + execute immediately. + +As an example, consider the following snippet: + + print (if { = @var foo } { + quote 'Hello world\n' + } else { + quote 'Error\n' + }) + +which gets expanded to the following: + + ((print (if (quote ((= (set var) foo))) + (quote ((quote 'Hello world\n'))) + else + (quote ((quote 'Error\n')))))) + +Observe that the whole program is enclosed in an implicit pair of `{}` and that +`quote` is a very powerful special form which can replace many others if needed. + +Runtime +------- +All variables are put in a single global namespace with no further scoping. +When calling a command (which is a list of lists), all arguments are +automatically stored in variables named 1, 2, 3, ... n. They are however +effectively inaccessible and you must rename them first using the `arg` special +form. + +When evaluating a command, the first argument is typically a string with its +name and it is resolved as if `set` was called on it. + +The last expression in a block is the return value. + +Special forms +------------- +`quote <arg>` + +Returns the first argument. + +`arg <name>...` + +Reassigns arguments to the current call in order to given names. This must be a +special form because of the lack of variable scoping. It needs to see arguments +from the other scope. + +Standard library +---------------- +`if <cond> <body> [elif <cond> <body>]... [else <body>]` + +Conditional evaluation, strings evaluate to themselves. + +`funargs` + +Returns arguments to the current evaluation context as a list. + +Contributing and Support +------------------------ +Use this project's GitHub to report any bugs, request features, or submit pull +requests. If you want to discuss this project, or maybe just hang out with +the developer, feel free to join me at irc://irc.janouch.name, channel #dev. + +License +------- +'ell' is written by Přemysl Janouch <p.janouch@gmail.com>. + +You may use the software under the terms of the ISC license, the text of which +is included within the package, or, at your option, you may relicense the work +under the MIT or the Modified BSD License, as listed at the following site: + +http://www.gnu.org/licenses/license-list.html |