Provided by: ocaml-man_5.3.0-3_all 
NAME
Misc - Miscellaneous useful types and functions
Module
Module Misc
Documentation
Module Misc
: sig end
Miscellaneous useful types and functions
Warning: this module is unstable and part of Compiler_libs .
Reporting fatal errors
val fatal_error : string -> 'a
Raise the Fatal_error exception with the given string.
val fatal_errorf : ('a, Format.formatter, unit, 'b) format4 -> 'a
Format the arguments according to the given format string and raise Fatal_error with the resulting
string.
exception Fatal_error
Exceptions and finalization
val try_finally : ?always:(unit -> unit) -> ?exceptionally:(unit -> unit) -> (unit -> 'a) -> 'a
try_finally work ~always ~exceptionally is designed to run code in work that may fail with an exception,
and has two kind of cleanup routines: always , that must be run after any execution of the function
(typically, freeing system resources), and exceptionally , that should be run only if work or always
failed with an exception (typically, undoing user-visible state changes that would only make sense if the
function completes correctly). For example:
let objfile = outputprefix ^ ".cmo" in
let oc = open_out_bin objfile in
Misc.try_finally
(fun () ->
bytecode
++ Timings.(accumulate_time (Generate sourcefile))
(Emitcode.to_file oc modulename objfile);
Warnings.check_fatal ())
~always:(fun () -> close_out oc)
~exceptionally:(fun _exn -> remove_file objfile);
If exceptionally fail with an exception, it is propagated as usual.
If always or exceptionally use exceptions internally for control-flow but do not raise, then try_finally
is careful to preserve any exception backtrace coming from work or always for easier debugging.
val reraise_preserving_backtrace : exn -> (unit -> unit) -> 'a
reraise_preserving_backtrace e f is (f (); raise e) except that the current backtrace is preserved, even
if f uses exceptions internally.
List operations
val map_end : ('a -> 'b) -> 'a list -> 'b list -> 'b list
map_end f l t is map f l @ t , just more efficient.
val rev_map_end : ('a -> 'b) -> 'a list -> 'b list -> 'b list
map_end f l t is map f (rev l) @ t , just more efficient.
val map_left_right : ('a -> 'b) -> 'a list -> 'b list
Like List.map , with guaranteed left-to-right evaluation order
val for_all2 : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool
Same as List.for_all but for a binary predicate. In addition, this for_all2 never fails: given two lists
with different lengths, it returns false.
val replicate_list : 'a -> int -> 'a list
replicate_list elem n is the list with n elements all identical to elem .
val list_remove : 'a -> 'a list -> 'a list
list_remove x l returns a copy of l with the first element equal to x removed.
val split_last : 'a list -> 'a list * 'a
Return the last element and the other elements of the given list.
Hash table operations
val create_hashtable : int -> ('a * 'b) list -> ('a, 'b) Hashtbl.t
Create a hashtable with the given initial size and fills it with the given bindings.
Extensions to the standard library
module Stdlib : sig end
Operations on files and file paths
val find_in_path : string list -> string -> string
Search a file in a list of directories.
val find_in_path_rel : string list -> string -> string
Search a relative file in a list of directories.
val normalized_unit_filename : string -> (string, string) Result.t
Normalize file name Foo.ml to foo.ml , using NFC and case-folding. Return Error if the input is not a
valid utf-8 byte sequence
val find_in_path_normalized : string list -> string -> string
Same as Misc.find_in_path_rel , but search also for normalized unit filename, i.e. if name is Foo.ml ,
allow /path/Foo.ml and /path/foo.ml to match.
val remove_file : string -> unit
Delete the given file if it exists and is a regular file. Does nothing for other kinds of files. Never
raises an error.
val expand_directory : string -> string -> string
expand_directory alt file eventually expands a + at the beginning of file into alt (an alternate root
directory)
val split_path_contents : ?sep:char -> string -> string list
split_path_contents ?sep s interprets s as the value of a "PATH"-like variable and returns the
corresponding list of directories. s is split using the platform-specific delimiter, or ~sep if it is
passed.
Returns the empty list if s is empty.
val copy_file : in_channel -> out_channel -> unit
copy_file ic oc reads the contents of file ic and copies them to oc . It stops when encountering EOF on
ic .
val copy_file_chunk : in_channel -> out_channel -> int -> unit
copy_file_chunk ic oc n reads n bytes from ic and copies them to oc . It raises End_of_file when
encountering EOF on ic .
val string_of_file : in_channel -> string
string_of_file ic reads the contents of file ic and copies them to a string. It stops when encountering
EOF on ic .
val output_to_file_via_temporary : ?mode:open_flag list -> string -> (string -> out_channel -> 'a) -> 'a
Produce output in temporary file, then rename it (as atomically as possible) to the desired output file
name. output_to_file_via_temporary filename fn opens a temporary file which is passed to fn (name +
output channel). When fn returns, the channel is closed and the temporary file is renamed to filename .
val protect_writing_to_file : filename:string -> f:(out_channel -> 'a) -> 'a
Open the given filename for writing (in binary mode), pass the out_channel to the given function, then
close the channel. If the function raises an exception then filename will be removed.
val concat_null_terminated : string list -> string
concat_null_terminated [x1;x2; ... xn] is x1 ^ "\000" ^ x2 ^ "\000" ^ ... ^ xn ^ "\000"
val split_null_terminated : string -> string list
split_null_terminated s is similar String.split_on_char '\000' but ignores the trailing separator, if any
val chop_extensions : string -> string
Return the given file name without its extensions. The extensions is the longest suffix starting with a
period and not including a directory separator, .xyz.uvw for instance.
Return the given name if it does not contain an extension.
Integer operations
val log2 : int -> int
log2 n returns s such that n = 1 lsl s if n is a power of 2
val align : int -> int -> int
align n a rounds n upwards to a multiple of a (a power of 2).
val no_overflow_add : int -> int -> bool
no_overflow_add n1 n2 returns true if the computation of n1 + n2 does not overflow.
val no_overflow_sub : int -> int -> bool
no_overflow_sub n1 n2 returns true if the computation of n1 - n2 does not overflow.
val no_overflow_mul : int -> int -> bool
no_overflow_mul n1 n2 returns true if the computation of n1 * n2 does not overflow.
val no_overflow_lsl : int -> int -> bool
no_overflow_lsl n k returns true if the computation of n lsl k does not overflow.
val letter_of_int : int -> string
module Int_literal_converter : sig end
val find_first_mono : (int -> bool) -> int
find_first_mono p takes an integer predicate p : int -> bool that we assume: 1. is monotonic on natural
numbers: if a <= b then p a implies p b , 2. is satisfied for some natural numbers in range 0; max_int
(this is equivalent to: p max_int = true ).
find_first_mono p is the smallest natural number N that satisfies p , computed in O(log(N)) calls to p .
Our implementation supports two cases where the preconditions on p are not respected:
-If p is always false , we silently return max_int instead of looping or crashing.
-If p is non-monotonic but eventually true, we return some satisfying value.
String operations
val search_substring : string -> string -> int -> int
search_substring pat str start returns the position of the first occurrence of string pat in string str .
Search starts at offset start in str . Raise Not_found if pat does not occur.
val replace_substring : before:string -> after:string -> string -> string
replace_substring ~before ~after str replaces all occurrences of before with after in str and returns the
resulting string.
val rev_split_words : string -> string list
rev_split_words s splits s in blank-separated words, and returns the list of words in reverse order.
val cut_at : string -> char -> string * string
String.cut_at s c returns a pair containing the sub-string before the first occurrence of c in s , and
the sub-string after the first occurrence of c in s . let (before, after) = String.cut_at s c in
before ^ String.make 1 c ^ after is the identity if s contains c .
Raise Not_found if the character does not appear in the string
Since 4.01
val ordinal_suffix : int -> string
ordinal_suffix n is the appropriate suffix to append to the numeral n as an ordinal number: 1 -> "st" , 2
-> "nd" , 3 -> "rd" , 4 -> "th" , and so on. Handles larger numbers (e.g., 42 -> "nd" ) and the numbers
11--13 (which all get "th" ) correctly.
val normalise_eol : string -> string
normalise_eol s returns a fresh copy of s with any '\r' characters removed. Intended for pre-processing
text which will subsequently be printed on a channel which performs EOL transformations (i.e. Windows)
val delete_eol_spaces : string -> string
delete_eol_spaces s returns a fresh copy of s with any end of line spaces removed. Intended to normalize
the output of the toplevel for tests.
Operations on references
type ref_and_value =
| R : 'a ref * 'a -> ref_and_value
val protect_refs : ref_and_value list -> (unit -> 'a) -> 'a
protect_refs l f temporarily sets r to v for each R (r, v) in l while executing f . The previous contents
of the references is restored even if f raises an exception, without altering the exception backtrace.
val get_ref : 'a list ref -> 'a list
get_ref lr returns the content of the list reference lr and reset its content to the empty list.
val set_or_ignore : ('a -> 'b option) -> 'b option ref -> 'a -> unit
set_or_ignore f opt x sets opt to f x if it returns Some _ , or leaves it unmodified if it returns None .
Operations on triples and quadruples
val fst3 : 'a * 'b * 'c -> 'a
val snd3 : 'a * 'b * 'c -> 'b
val thd3 : 'a * 'b * 'c -> 'c
val fst4 : 'a * 'b * 'c * 'd -> 'a
val snd4 : 'a * 'b * 'c * 'd -> 'b
val thd4 : 'a * 'b * 'c * 'd -> 'c
val for4 : 'a * 'b * 'c * 'd -> 'd
Spell checking and ``did you mean'' suggestions
val edit_distance : string -> string -> int -> int option
edit_distance a b cutoff computes the edit distance between strings a and b . To help efficiency, it uses
a cutoff: if the distance d is smaller than cutoff , it returns Some d , else None .
The distance algorithm currently used is Damerau-Levenshtein: it computes the number of insertion,
deletion, substitution of letters, or swapping of adjacent letters to go from one word to the other. The
particular algorithm may change in the future.
val spellcheck : string list -> string -> string list
spellcheck env name takes a list of names env that exist in the current environment and an erroneous name
, and returns a list of suggestions taken from env , that are close enough to name that it may be a typo
for one of them.
val did_you_mean : Format_doc.formatter -> (unit -> string list) -> unit
did_you_mean ppf get_choices hints that the user may have meant one of the option returned by calling
get_choices . It does nothing if the returned list is empty.
The unit -> ... thunking is meant to delay any potentially-slow computation (typically computing
edit-distance with many things from the current environment) to when the hint message is to be printed.
You should print an understandable error message before calling did_you_mean , so that users get a clear
notification of the failure even if producing the hint is slow.
module Color : sig end
Color support detection
Styling handling for terminal output
module Style : sig end
module Error_style : sig end
Formatted output
val print_if : Format.formatter -> bool ref -> (Format.formatter -> 'a -> unit) -> 'a -> 'a
print_if ppf flag fmt x prints x with fmt on ppf if b is true.
val print_see_manual : int list Format_doc.printer
See manual section
Displaying configuration variables
val show_config_and_exit : unit -> unit
Display the values of all compiler configuration variables from module Config , then exit the program
with code 0.
val show_config_variable_and_exit : string -> unit
Display the value of the given configuration variable, then exit the program with code 0.
Handling of build maps
Build maps cause the compiler to normalize file names embedded in object files, thus leading to more
reproducible builds.
val get_build_path_prefix_map : unit -> Build_path_prefix_map.map option
Returns the map encoded in the BUILD_PATH_PREFIX_MAP environment variable.
val debug_prefix_map_flags : unit -> string list
Returns the list of --debug-prefix-map flags to be passed to the assembler, built from the
BUILD_PATH_PREFIX_MAP environment variable.
Handling of magic numbers
module Magic_number : sig end
Minimal support for Unicode characters in identifiers
Characters allowed in identifiers are, currently:
-ASCII letters A-Z a-z
-Latin-1 letters (U+00C0 - U+00FF except U+00D7 and U+00F7)
-Character sequences which normalize to the above character under NFC
-digits 0-9, underscore, single quote
module Utf8_lexeme : sig end
Miscellaneous type aliases
type filepath = string
type modname = string
type crcs = (modname * Digest.t option) list
type alerts = string Stdlib.String.Map.t
OCamldoc 2025-06-12 Misc(3o)