diff options
Diffstat (limited to 'README.adoc')
| -rw-r--r-- | README.adoc | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/README.adoc b/README.adoc index c091259..0cb914c 100644 --- a/README.adoc +++ b/README.adoc @@ -25,8 +25,8 @@ 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. + wrapped in parentheses, and the resulting sequence is wrapped in a quoted + list, so that it doesn't execute immediately. As an example, consider the following snippet: @@ -38,13 +38,13 @@ As an example, consider the following snippet: which gets expanded to the following: - ((print (if (quote ((eq? (set var) foo))) - (quote ((values 'Hello world\n'))) + ((print (if (block (eq? (set var) foo)) + (block (values 'Hello world\n')) else - (quote ((values 'Error\n')))))) + (block (values '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. +`block` is all that's left of special forms. For a slightly more realistic example you can have a look at 'greet.ell'. @@ -55,20 +55,27 @@ of lists) are assigned to local variables named `1`, `2`, etc., and the full list of them is stored in `args`. 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. +name and it is resolved as if `set` was called on it. Lists are left for +execution as they are. The last expression in a block is the return value. Special Forms ------------- -`quote [<arg>]...` +`block [<arg>]...` -Like `values` but returns the arguments without any evaluation. +Like `list` but doesn't evaluate arguments. A more appropriate name might be +`quoted-list`, which is not as descriptive in terms of syntax. If simple +quoting is desired, the list can be unpacked by an ordinary command. -Standard library +Standard Library ---------------- The standard library interprets the empty list and the empty string as false -values, everything else is taken as true. +values, everything else is considered true. Numbers are floating point with +double precision, trailing zeroes are truncated. + +Where a `<body>` is expected, strings retain their value, and block evaluation +is postponed as necessary. `local <names> [<value>]...` @@ -89,7 +96,7 @@ Return an arbitrary number of values. `if <cond> <body> [elif <cond> <body>]... [else <body>]` -Conditional evaluation, strings evaluate to themselves. +Conditional evaluation. `for <list> <body>` @@ -129,7 +136,7 @@ Execute the body and pass any error to the handler instead of propagating it. `throw <message>` -Throw an error. Messages starting on an underscore don't generate backtraces +Throw an error. Messages starting on an underscore don't generate backtraces, which can be used to catch them. `not <value>` |