js_float.ml

(* Copyright (C) 2015-2016 Bloomberg Finance L.P.
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition to the permissions granted to you by the LGPL, you may combine
 * or link a "work that uses the Library" with a publicly distributed version
 * of this file to produce a combined library or application, then distribute
 * that combined work under the terms of your choosing, with no requirement
 * to comply with the obligations normally placed on you by section 4 of the
 * LGPL version 3 (or the corresponding section of a later version of the LGPL
 * should you choose to use a later version).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *)

(** Provides functions for inspecting and manipulating [float]s
*)

(** The special value "Not a Number"

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN> MDN
*)
external _NaN : float = "NaN" [@@bs.val] 

(** Tests if the given value is [_NaN]

Note that both [_NaN = _NaN] and [_NaN == _NaN] will return [false]. [isNaN] is
therefore necessary to test for [_NaN].

{b Returns} [true] if the given value is [_NaN], [false] otherwise

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN> MDN
*)
external isNaN : float -> bool = "" [@@bs.val]

(** Tests if the given value is finite

{b Returns} [true] if the given value is a finite number, [false] otherwise

@example {[
(* returns [false] *)
let _ = Js.Float.isFinite infinity

(* returns [false] *)
let _ = Js.Float.isFinite neg_infinity

(* returns [false] *)
let _ = Js.Float.isFinite _NaN

(* returns [true] *)
let _ = Js.Float.isFinite 1234
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isFinite> MDN
*)
external isFinite : float -> bool = "" [@@bs.val]

(** Formats a [float] using exponential (scientific) notation

{b Returns} a [string] representing the given value in exponential notation

@raise RangeError if digits is not in the range \[0, 20\] (inclusive)

@example {[
(* prints "7.71234e+1" *)
let _ = Js.log \@\@ Js.Float.toExponential 77.1234

(* prints "7.7e+1" *)
let _ = Js.log \@\@ Js.Float.toExponential 77.
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toExponential> MDN
*)
external toExponential : float -> string = "" [@@bs.send]

(** Formats a [float] using exponential (scientific) notation

{b digits} specifies how many digits should appear after the decimal point. The
value must be in the range \[0, 20\] (inclusive).

{b Returns} a [string] representing the given value in exponential notation

The output will be rounded or padded with zeroes if necessary.

@raise RangeError if digits is not in the range \[0, 20\] (inclusive)

@example {[
(* prints "7.71e+1" *)
let _ = Js.log \@\@ Js.Float.toExponentialWithPrecision 77.1234 ~digits:2
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toExponential> MDN
*)
external toExponentialWithPrecision : float -> digits:int -> string = "toExponential" [@@bs.send]

(** Formats a [float] using fixed point notation

{b Returns} a [string] representing the given value in fixed-point notation (usually)

@raise RangeError if digits is not in the range \[0, 20\] (inclusive)

@example {[
(* prints "12346" (note the rounding) *)
let _ = Js.log \@\@ Js.Float.toFixed 12345.6789

(* print "1.2e+21" *)
let _ = Js.log \@\@ Js.Float.toFixed 1.2e21
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed> MDN
*)
external toFixed : float -> string = "" [@@bs.send]

(** Formats a [float] using fixed point notation

{b digits} specifies how many digits should appear after the decimal point. The
value must be in the range \[0, 20\] (inclusive). Defaults to [0].

{b Returns} a [string] representing the given value in fixed-point notation (usually)

The output will be rounded or padded with zeroes if necessary.

@raise RangeError if digits is not in the range \[0, 20\] (inclusive)

@example {[
(* prints "12345.7" (note the rounding) *)
let _ = Js.log \@\@ Js.Float.toFixedWithPrecision 12345.6789 ~digits:1

(* prints "0.00" (note the added zeroes) *)
let _ = Js.log \@\@ Js.Float.toFixedWithPrecision 0. ~digits:2
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed> MDN
*)
external toFixedWithPrecision : float -> digits:int -> string = "toFixed" [@@bs.send]

(** Formats a [float] using some fairly arbitrary rules

{b Returns} a [string] representing the given value in fixed-point (usually)

[toPrecision] differs from [toFixed] in that the former will format the number
with full precision, while the latter will not output any digits after the
decimal point.

@raise RangeError if digits is not in the range accepted by this function (what do you mean "vague"?)

@example {[
(* prints "12345.6789" *)
let _ = Js.log \@\@ Js.Float.toPrecision 12345.6789

(* print "1.2e+21" *)
let _ = Js.log \@\@ Js.Float.toPrecision 1.2e21
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toPrecision> MDN
*)
external toPrecision : float -> string = "" [@@bs.send] (* equivalent to `toString` I think *)

(** Formats a [float] using some fairly arbitrary rules

{b digits} specifies how many digits should appear in total. The
value must between 0 and some arbitrary number that's hopefully at least larger
than 20 (for Node it's 21. Why? Who knows).

{b Returns} a [string] representing the given value in fixed-point or scientific notation

The output will be rounded or padded with zeroes if necessary.

[toPrecisionWithPrecision] differs from [toFixedWithPrecision] in that the former
will count all digits against the precision, while the latter will count only
the digits after the decimal point. [toPrecisionWithPrecision] will also use
scientific notation if the specified precision is less than the number for digits
before the decimal point.

@raise RangeError if digits is not in the range accepted by this function (what do you mean "vague"?)

@example {[
(* prints "1e+4" *)
let _ = Js.log \@\@ Js.Float.toPrecisionWithPrecision 12345.6789 ~digits:1

(* prints "0.0" *)
let _ = Js.log \@\@ Js.Float.toPrecisionWithPrecision 0. ~digits:2
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toPrecision> MDN
*)
external toPrecisionWithPrecision : float -> digits:int -> string = "toPrecision" [@@bs.send]


(** Formats a [float] as a string

{b Returns} a [string] representing the given value in fixed-point (usually)

@example {[
(* prints "12345.6789" *)
let _ = Js.log \@\@ Js.Float.toString 12345.6789
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toString> MDN
*)
external toString : float -> string = "" [@@bs.send]

(** Formats a [float] as a string

{b radix} specifies the radix base to use for the formatted number. The
value must be in the range \[2, 36\] (inclusive).

{b Returns} a [string] representing the given value in fixed-point (usually)

@raise RangeError if radix is not in the range \[2, 36\] (inclusive)

@example {[
(* prints "110" *)
let _ = Js.log \@\@ Js.Float.toStringWithRadix 6. ~radix:2

(* prints "11.001000111101011100001010001111010111000010100011111" *)
let _ = Js.log \@\@ Js.Float.toStringWithRadix 3.14 ~radix:2

(* prints "deadbeef" *)
let _ = Js.log \@\@ Js.Float.toStringWithRadix 3735928559. ~radix:16

(* prints "3f.gez4w97ry0a18ymf6qadcxr" *)
let _ = Js.log \@\@ Js.Float.toStringWithRadix 123.456 ~radix:36
]}

@see <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toString> MDN
*)
external toStringWithRadix : float -> radix:int -> string = "toString" [@@bs.send]

(** Parses the given [string] into a [float] using JavaScript semantics

{b Returns} the number as a [float] if successfully parsed, [_NaN] otherwise.

@example {[
(* returns 123 *)
let _ = Js.Float.fromString "123"

(* returns 12.3 *)
let _ = Js.Float.fromString "12.3"

(* returns 0 *)
let _ = Js.Float.fromString ""

(* returns 17 *)
let _ = Js.Float.fromString "0x11"

(* returns 3 *)
let _ = Js.Float.fromString "0b11"

(* returns 9 *)
let _ = Js.Float.fromString "0o11"

(* returns [_NaN] *)
let _ = Js.Float.fromString "foo"

(* returns [_NaN] *)
let _ = Js.Float.fromString "100a"
]}
*)
external fromString : string -> float = "Number" [@@bs.val]