MODULE
lfe_io
MODULE SUMMARY
Lisp Flavoured Erlang (LFE) io functions
DESCRIPTION
This module provides a standard set of io functions for
LFE. In the following description, many functions have an
optional parameter IoDevice. If included, it must be the pid
of a process which handles the IO protocols such as the
IoDevice returned by file:open/2.
Two functions in this module are used to generate
aesthetically attractive representations of abstract forms,
which are suitable for printing. These functions return
(possibly deep) lists of characters and generate an error if
the form is wrong.
DATA TYPES
chars() = [char() | chars()]
filesexpr() = {Sexpr,Line}
This is the format returned by lfe_io:parse_file/1 and
is used by the compiler to give better error
information.
EXPORTS
read([IoDevice]) -> Sexpr
Read an s-expr from the standard input (IoDevice).
print([IoDevice,] Sexpr) -> ok
Print the s-expr Sexpr to the standard output (IoDevice).
prettyprint([IoDevice,] Sexpr) -> ok
Pretty print the s-expr Sexpr to the standard output
(IoDevice). Assume we start with no indentation.
print1(Sexpr) -> DeepCharList
Return the list of characters which represent the s-expr Sexpr.
prettyprint1(Sexpr, CurrentIndentation) -> DeepCharList
Return the lost of characters which represents the
prettyprinted s-expr Sexpr. Assume we start at indentation
CurrentIndentation.
print1_symb(Symbol) -> DeepCharList.
Return the list of characters needed to print the symbol Symbol.
print1_string(String) -> DeepCharList.
Return the list of characters needed to print the string
String as a string.
format([IoDevice,] Format, Args) -> ok
format1(Format, Args) -> DeepCharList
Print formatted output. The following commands are valid in
the format string:
~w, ~W - print LFE terms
~p, ~P - prettyprint LFE terms
~s - print a string
~e, ~f, ~g - print floats
~b, ~B - based integers
~x, ~X - based integers with a prefix
~+, ~# - based integers in vanilla erlang format
~c, ~n, ~i
Currently they behave as for vanilla erlang except that ~w,
~W, ~p, ~P print the terms as LFE sexprs.
read_file(FileName) -> {ok,[Sexpr]} | {error,ErrorInfo}
Read the file Filename returning a list of s-exprs (as it
should be).
parse_file(FileName) -> {ok,[FileSexpr]} | {error,ErrorInfo}
where
FileSexpr = filesexpr()
Read the file Filename returning a list of pairs containing
s-expr and line number of the start of the s-expr.
Error Information
The ErrorInfo mentioned above is the standard ErrorInfo
structure which is returned from all IO modules. It has the
following format:
{ErrorLine,Module,ErrorDescriptor}
A string describing the error is obtained with the following call:
apply(Module, format_error, ErrorDescriptor)