GIML: How to use files

Reading programs

The use command takes a file name and parses and executes the contents as an SML program. The use instruction may of course appear in these files. Comments are enclosed in (* *) pairs.

Reading data

The following are available (among other)

`open_in`	`string -> instream`	Create an input stream
`input_line`	`instream -> string`	Get one line
`end_of_stream`	`instream -> boolean`	Check for more
`can_input`	`instream -> int`	Check for more
`input`	`instream * int -> string`	Get loads
`close_in`	`instream -> unit`

Handling input & output efficiently can be tricky. So don't bother, use one of the following to load an entire file into either a single string or a list of strings - let the operating system do the work.

fun fileToString fileName = let
  val stream = open_in fileName
  val str = input(stream, can_input stream)
  val _ = close_in stream
in str end;

fun fileToList fileName = let
  fun f fh = if end_of_stream fh then
    let val _ = close_in fh in nil end
    else (input_line fh)::(f fh)
in f(open_in fileName) end;

Writing data

This is very similar you have

open_out : string -> outstream
open_append : string -> outstream
output : outstream * string -> unit
flush_out : outstream -> unit
close_out : outstream -> unit

A list of the IO structure

exception Io = Io val std_in = - : instream val std_out = - : outstream val std_err = - : outstream val open_in = fn : string -> instream val open_out = fn : string -> outstream val open_append = fn : string -> outstream val open_string = fn : string -> instream val close_in = fn : instream -> unit val close_out = fn : outstream -> unit val output = fn : outstream * string -> unit val outputc = fn : outstream -> string -> unit val input = fn : instream * int -> string val inputc = fn : instream -> int -> string val input_line = fn : instream -> string val lookahead = fn : instream -> string val end_of_stream = fn : instream -> bool val can_input = fn : instream -> int val flush_out = fn : outstream -> unit val is_term_in = fn : instream -> bool val is_term_out = fn : outstream -> bool val set_term_in = fn : instream * bool -> unit val set_term_out = fn : outstream * bool -> unit val execute = fn : string * string list -> instream * outstream val execute_in_env = fn : string * string list * string list -> instream * outstream val exportML = fn : string -> bool val exportFn = fn : string * (string list * string list -> unit) -> unit