Module type `Record_in_channel.S`Source

An input channel for reading (biological) records.

Overview

Quick start

To get a list of records, use records or with_file_records.
To get a sequence of records, use: record_sequence.
To fold over records, use: fold_records or with_file_fold_records.
To iterate over records, use: iter_records or with_file_iter_records.

For some more info, check out the usage examples.

Function flavors

Most functions in this module come in a few different flavors.

Functions with with_file_ prefix
Functions with the _exn suffix
Functions that return Or_error.t

Functions that have the with_file_ prefix in their name take a filename string rather than a t. They are a convenient way to avoid wrapping your all your code in with_file function calls.

Functions that the _exn suffix in their name may raise exceptions, either from logic specific to this module, or from calls to other Core_kernel functions.

Functions that return Or_error.t catch all exceptions, even those not originating in the logic of this module. These functions shouldn't raise in practice. In other words, if you aren't using a function with _exn in the name, and you get an exception, then you have found a bug.

Here is an example of the different "flavors" of fold_records:

fold_records: the normal t accepting, Or_error.t returning flavor
fold_records_exn: takes t but may raise exceptions instead of returning Or_error.t
with_file_fold_records: takes a file name (string) rather than a t, and returns Or_error.t
with_file_fold_records_exn: takes a file name (string) rather than a t, and may raise exceptions

API

type t

type record

val stdin : t

create_exn file_name opens an t on the standard input channel.

val create_exn : Base.string -> t

create_exn file_name opens an input channel on the file specified by file_name.

val create : Base.string -> t Base.Or_error.t

create file_name opens an input channel on the file specified by file_name.

val close_exn : t -> Base.unit

close_exn t Close the t. Raises if the call fails.

val close : t -> Base.unit Base.Or_error.t

close t is like close_exnt t except that it shouldn't raise.

val with_file_exn : Base.string -> f:(t -> 'a) -> 'a

with_file_exn file_name ~f executes ~f on the channel created from file_name and closes it afterwards.

val with_file : Base.string -> f:(t -> 'a) -> 'a Base.Or_error.t

with_file file_name ~f is like with_file_exn file_name ~f except that it shouldn't raise.

val equal : t -> t -> Base.bool

equal t1 t2 compares t1 and t2 for equality.

val input_record_exn : t -> record Base.option

input_record_exn t returns Some record if there is a record to return. If there are no more records, None is returned. Exn is raised on bad input.

val input_record : t -> record Base.option Base.Or_error.t

input_record t is like input_record_exn t except that it should not raise exceptions.

Folding over records

val fold_records_exn : t -> init:'a -> f:('a -> record -> 'a) -> 'a

fold_records_exn t ~init ~f reduces all records from a t down to a single value of type 'a.

val fold_records : t -> init:'a -> f:('a -> record -> 'a) -> 'a Base.Or_error.t

fold_records t ~init ~f is like fold_records_exn t ~init ~f except that it should not raise exceptions. Rather than deal with exceptions inside the reducing function, you must deal with them at the end when handling the return value.

val foldi_records_exn : 
  t ->
  init:'a ->
  f:(Base.int -> 'a -> record -> 'a) ->
  'a

Like fold_records_exn t ~init ~f except that f is provided the 0-based record index as its first argument. See fold_records_exn.

val foldi_records : 
  t ->
  init:'a ->
  f:(Base.int -> 'a -> record -> 'a) ->
  'a Base.Or_error.t

Like foldi_records_exn t ~init ~f except that it shouldn't raise. See foldi_records_exn.

Folding with file name

val with_file_fold_records_exn : 
  Base.string ->
  init:'a ->
  f:('a -> record -> 'a) ->
  'a

with_file_fold_records_exn file_name ~init ~f is like fold_records_exn t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_fold_records : 
  Base.string ->
  init:'a ->
  f:('a -> record -> 'a) ->
  'a Base.Or_error.t

with_file_fold_records file_name ~init ~f is like fold_records t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_foldi_records_exn : 
  Base.string ->
  init:'a ->
  f:(Base.int -> 'a -> record -> 'a) ->
  'a

with_file_foldi_records_exn file_name ~init ~f is like foldi_records_exn t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_foldi_records : 
  Base.string ->
  init:'a ->
  f:(Base.int -> 'a -> record -> 'a) ->
  'a Base.Or_error.t

with_file_foldi_records file_name ~init ~f is like fold'_records t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

Iterating over records

The iter functions are like the fold functions except they do not take an init value and the f function returns unit insead of some other value 'a, and thus return unit rather than a value 'a.

They are mainly called for side effects.

val iter_records_exn : t -> f:(record -> Base.unit) -> Base.unit

iter_records_exn t ~f calls f on each record in t. As f returns unit this is generally used for side effects.

val iter_records : t -> f:(record -> Base.unit) -> Base.unit Base.Or_error.t

iter_records t ~f is like iter_records_exn t ~f except that it shouldn't raise.

val iteri_records_exn : t -> f:(Base.int -> record -> Base.unit) -> Base.unit

iteri_records_exn t ~f is like iteri_records_exn t ~f except that f is passed in the 0-indexed record index as its first argument.

val iteri_records : 
  t ->
  f:(Base.int -> record -> Base.unit) ->
  Base.unit Base.Or_error.t

iteri_records t ~f is like iteri_records_exn t ~f except that it shouldn't raise.

Iterating with file name

val with_file_iter_records_exn : 
  Base.string ->
  f:(record -> Base.unit) ->
  Base.unit

with_file_iter_records_exn file_name ~init ~f is like iter_records_exn t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_iter_records : 
  Base.string ->
  f:(record -> Base.unit) ->
  Base.unit Base.Or_error.t

with_file_iter_records file_name ~init ~f is like iter_records t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_iteri_records_exn : 
  Base.string ->
  f:(Base.int -> record -> Base.unit) ->
  Base.unit

with_file_iteri_records_exn file_name ~init ~f is like iteri_records_exn t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

val with_file_iteri_records : 
  Base.string ->
  f:(Base.int -> record -> Base.unit) ->
  Base.unit Base.Or_error.t

with_file_iteri_records file_name ~init ~f is like iteri_records t ~init ~f except that it is passed a file name, and it manages t automatically. See with_file.

Getting records as a list

These functions return lists of recordss.

val records_exn : t -> record Base.List.t

val records : t -> record Base.List.t Base.Or_error.t

With file name

val with_file_records_exn : Base.string -> record Base.List.t

val with_file_records : Base.string -> record Base.List.t Base.Or_error.t

Getting records as a sequence

These are a bit different:

* There are no with_file versions as you would have to do some fiddly things to keep the channel open, making them not so nice to use.

* Each record that is yielded is wrapped in an Or_error.t. This is different from the iter, fold, and other non _exn functions in which case the entire result is wrapped in an Or_error.t, letting you ignore errors in the passed in ~f function and deal with failure once.

val record_sequence_exn : t -> record Base.Sequence.t

record_sequence_exn t returns a Sequence.t of record. May raise exceptions.

val record_sequence : t -> record Base.Or_error.t Base.Sequence.t

record_sequence t is like record_sequence_exn t except that instead of raising exceptions, each item of the sequence is a record Or_error.t rather than an "unwrapped" record. This could make things annoying to deal with. If you don't want exceptions, you could instead wrap your entire sequence processing pipeline in a call to with_file and handle the Or_error.t in that way. See the pipelines usage examples for more info.

package bio_io

Module type Record_in_channel.SSource