Previous  Up  Next

Module Streamutil


module Streamutil: sig .. end
Stream creation, parsing, and manipulation utilities
Author(s): Copyright (C) 2004 John Goerzen

Stream generation

These functions create new streams.

val of_channel_lines : Pervasives.in_channel -> string Stream.t
Given an input file descriptor, generates a stream that yields each line of the input file.
val of_channel_blocks : Pervasives.in_channel -> int -> string Stream.t
Given an input file descriptor and a blocksize, generates a stream that yields blocks of the given blocksize. The very last block in the stream may have a lower size if the input does not end on an even block boundary. All other blocks are guaranteed to match the given block size.

Stream Conversion Utilities

These utilities work on streams, returning a new lazy stream that reflects the changes.

val filter : ('a -> bool) -> 'a Stream.t -> 'a Stream.t
Given a function, returns a new stream with all the elements of the original stream for which func returns true.
val map : ('a -> 'b) -> 'a Stream.t -> 'b Stream.t
Given a function, returns a new stream with the results of func applied to each element.
val map_stream : ('a -> 'b Stream.t) -> 'a Stream.t -> 'b Stream.t
Given a function, returns a new stream with the results of func applied to each element.

Unlike Streamutil.map, which expects func to take a single element and return a single element, this function expects func to take a single element and return a stream. This is a powerful capability that allows func to grow or shrink the results of processing the single element.

val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b Stream.t -> 'a
Given a function and an initial argument, calls the function on each element in the stream. Similar to List.fold_left.
val to_list : 'a Stream.t -> 'a list
Converts a stream to a list. WARNING: this will crash your program if used on infinite or very large streams. Use only on finite streams!
val take : int -> 'a Stream.t -> 'a Stream.t
Returns a finite stream representing the first n elements from the given stream.
val drop : int -> 'a Stream.t -> unit
Removes the first n elements from the start of the given stream. Unlike operations on lists, this is a destructive operation.

Stream processing utilities

These do something with a stream, and generally consume its elements completely.

val output_lines : Pervasives.out_channel -> string Stream.t -> unit
Given a stream of lines (such as created with Streamutil.of_channel_lines, output a line containing each element from the stream. The input stream is expected to not have newlines (those will be added automaticaly.)
val output_chars : Pervasives.out_channel -> char Stream.t -> unit
Given a stream of characters (such as created with Stream.of_channel), output the characters representing each element from the stream.

Stream parser utilities

These functions are used to parse streams.

val optparse : ('a -> 'b) -> 'b list -> 'a -> 'b list
This function is useful for parsing zero or more occurances of a certain element.
Returns A list of return values from func; may be empty.

func : The parser function. Will be called repeatedly until Stream.Failure is raised.
accum : Accumulator -- pass [] to it to start with.
args : Passed to func.
val optparse_1 : ('a -> 'b) -> ('a -> 'b) -> 'b list -> 'a -> 'b list
Same as optparse, but forces to match at least once. funchead is applied to the first element; functail to all the rest.

funchead : Function to apply to first element
functail : Function to apply to remaining arguments
accum : Accumulator -- pass [] to start with
args : Passed to the various functions
val optparse_1_folded : ('a -> 'b) -> ('c -> 'b -> 'c) -> 'c -> 'a -> 'c
Used to do something that happens once or more, and folds the results. Uses optparse_1 internally.

func : Parser function
combinefunc : Combination function used for folding
startval : Starting value for folding
args : Parser arguments
val optparse_1_string : ('a -> string) -> 'a -> string
Utility function used to generate strings; equivolent to optparse_1_folded func (^) "" args

func : Parser function
args : Arguments