Standard Library
Below is the API for the OCaml standard library. It's directly copied over from the OCaml Manual, formatted to the Reason syntax and styled accordingly. The API docs are work-in-progress; we'll be polishing these gradually!
If you're targeting JavaScript, the API docs for BuckleScript includes all of below, plus JS-specific APIs.
Module String
module String: sig .. endA string is an immutable data structure that contains a fixed-length sequence of (single-byte) characters. Each character can be accessed in constant time through its index.
Given a string s of length l, we can access each of the l
characters of s via its index in the sequence. Indexes start at
0, and we will call an index valid in s if it falls within the
range [0...l-1] (inclusive). A position is the point between two
characters or at the beginning or end of the string. We call a
position valid in s if it falls within the range [0...l]
(inclusive). Note that the character at index n is between
positions n and n+1.
Two parameters start and len are said to designate a valid
substring of s if len >= 0 and start and start+len are
valid positions in s.
OCaml strings used to be modifiable in place, for instance via the
String.set and String.blit functions described below. This
usage is deprecated and only possible when the compiler is put in
"unsafe-string" mode by giving the -unsafe-string command-line
option (which is currently the default for reasons of backward
compatibility). This is done by making the types string and
bytes (see module Bytes) interchangeable so that functions
expecting byte sequences can also accept strings as arguments and
modify them.
All new code should avoid this feature and be compiled with the
-safe-string command-line option to enforce the separation between
the types string and bytes.
val length : string -> int
val get : string -> int -> char
String.get s n returns the character at index n in string s.
You can also write s.[n] instead of String.get s n.
Raise Invalid_argument if n not a valid index in s.
val set : bytes -> int -> char -> unit
Bytes.set. String.set s n c modifies byte sequence s in place,
replacing the byte at index n with c.
You can also write s.[n] <- c instead of String.set s n c.
Raise Invalid_argument if n is not a valid index in s.
val create : int -> bytes
Bytes.create. String.create n returns a fresh byte sequence of length n.
The sequence is uninitialized and contains arbitrary bytes.
Raise Invalid_argument if n < 0 or n > Sys.max_string_length.
val make : int -> char -> string
String.make n c returns a fresh string of length n,
filled with the character c.
Raise Invalid_argument if n < 0 or n > Sys.max_string_length.
val init : int -> (int -> char) -> string
String.init n f returns a string of length n, with character
i initialized to the result of f i (called in increasing
index order).
Raise Invalid_argument if n < 0 or n > Sys.max_string_length.
Since 4.02.0
val copy : string -> string
Return a copy of the given string.
val sub : string -> int -> int -> string
String.sub s start len returns a fresh string of length len,
containing the substring of s that starts at position start and
has length len.
Raise Invalid_argument if start and len do not
designate a valid substring of s.
val fill : bytes -> int -> int -> char -> unit
Bytes.fill. String.fill s start len c modifies byte sequence s in place,
replacing len bytes with c, starting at start.
Raise Invalid_argument if start and len do not
designate a valid range of s.
val blit : string -> int -> bytes -> int -> int -> unit
Bytes.blit_string.val concat : string -> string list -> string
String.concat sep sl concatenates the list of strings sl,
inserting the separator string sep between each.
Raise Invalid_argument if the result is longer than
Sys.max_string_length bytes.
val iter : (char -> unit) -> string -> unit
String.iter f s applies function f in turn to all
the characters of s. It is equivalent to
f s.[0]; f s.[1]; ...; f s.[String.length s - 1]; ().val iteri : (int -> char -> unit) -> string -> unit
String.iter, but the
function is applied to the index of the element as first argument
(counting from 0), and the character itself as second argument.Since 4.00.0
val map : (char -> char) -> string -> string
String.map f s applies function f in turn to all the
characters of s (in increasing index order) and stores the
results in a new string that is returned.Since 4.00.0
val mapi : (int -> char -> char) -> string -> string
String.mapi f s calls f with each character of s and its
index (in increasing index order) and stores the results in a new
string that is returned.Since 4.02.0
val trim : string -> string
' ',
'\012', '\n', '\r', and '\t'. If there is neither leading nor
trailing whitespace character in the argument, return the original
string itself, not a copy.Since 4.00.0
val escaped : string -> string
Raise Invalid_argument if the result is longer than
Sys.max_string_length bytes.
val index : string -> char -> int
String.index s c returns the index of the first
occurrence of character c in string s.
Raise Not_found if c does not occur in s.
val rindex : string -> char -> int
String.rindex s c returns the index of the last
occurrence of character c in string s.
Raise Not_found if c does not occur in s.
val index_from : string -> int -> char -> int
String.index_from s i c returns the index of the
first occurrence of character c in string s after position i.
String.index s c is equivalent to String.index_from s 0 c.
Raise Invalid_argument if i is not a valid position in s.
Raise Not_found if c does not occur in s after position i.
val rindex_from : string -> int -> char -> int
String.rindex_from s i c returns the index of the
last occurrence of character c in string s before position i+1.
String.rindex s c is equivalent to
String.rindex_from s (String.length s - 1) c.
Raise Invalid_argument if i+1 is not a valid position in s.
Raise Not_found if c does not occur in s before position i+1.
val contains : string -> char -> bool
String.contains s c tests if character c
appears in the string s.val contains_from : string -> int -> char -> bool
String.contains_from s start c tests if character c
appears in s after position start.
String.contains s c is equivalent to
String.contains_from s 0 c.
Raise Invalid_argument if start is not a valid position in s.
val rcontains_from : string -> int -> char -> bool
String.rcontains_from s stop c tests if character c
appears in s before position stop+1.
Raise Invalid_argument if stop < 0 or stop+1 is not a valid
position in s.
val uppercase : string -> string
val lowercase : string -> string
val capitalize : string -> string
val uncapitalize : string -> string
type t = string
val compare : t -> t -> int
Pervasives.compare. Along with the type t, this function compare
allows the module String to be passed as argument to the functors
Set.Make and Map.Make.