Module Misc

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

Normalize file name Foo.ml to foo.ml

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

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.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 pp_two_columns : ?sep:string ->
       ?max_lines:int -> Format.formatter -> (string * string) list -> unit

pp_two_columns ?sep ?max_lines ppf l prints the lines in l as two columns separated by sep ("|" by default). max_lines can be used to indicate a maximum number of lines to print -- an ellipsis gets inserted at the middle if the input has too many lines.

Example:

pp_two_columns ~max_lines:3 Format.std_formatter [
      "abc", "hello";
      "def", "zzz";
      "a"  , "bllbl";
      "bb" , "dddddd";
    ]

prints

    abc | hello
    ...
    bb  | dddddd
   
val print_see_manual : Format.formatter -> int list -> unit

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

Miscellaneous type aliases

type filepath = string 
type modname = string 
type crcs = (modname * Digest.t option) list 
type alerts = string Stdlib.String.Map.t