Module `Misc`

Miscellaneous useful types and functions

Warning: this module is unstable and part of compiler-libs.

val fatal_error : string -> 'a
val fatal_errorf : ('a, Stdlib.Format.formatter, unit, 'b) Stdlib.format4 -> 'a

exception Fatal_error

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 map_end : ('a -> 'b) -> 'a list -> 'b list -> 'b list
val map_left_right : ('a -> 'b) -> 'a list -> 'b list
val for_all2 : ('a -> 'b -> bool) -> 'a list -> 'b list -> bool
val replicate_list : 'a -> int -> 'a list
val list_remove : 'a -> 'a list -> 'a list
val split_last : 'a list -> 'a list * 'a
val may : ('a -> unit) -> 'a option -> unit
val may_map : ('a -> 'b) -> 'a option -> 'b option

type ref_and_value = | R : 'a Stdlib.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.

module Stdlib : sig ... end

val find_in_path : string list -> string -> string
val find_in_path_rel : string list -> string -> string
val find_in_path_uncap : string list -> string -> string
val remove_file : string -> unit
val expand_directory : string -> string -> string
val split_path_contents : ?⁠sep:char -> string -> string list
val create_hashtable : int -> ('a * 'b) list -> ('a, 'b) Stdlib.Hashtbl.t
val copy_file : Stdlib.in_channel -> Stdlib.out_channel -> unit
val copy_file_chunk : Stdlib.in_channel -> Stdlib.out_channel -> int -> unit
val string_of_file : Stdlib.in_channel -> string
val output_to_file_via_temporary : ?⁠mode:Stdlib.open_flag list -> string -> (string -> Stdlib.out_channel -> 'a) -> 'a
val log2 : int -> int
val align : int -> int -> int
val no_overflow_add : int -> int -> bool
val no_overflow_sub : int -> int -> bool
val no_overflow_mul : int -> int -> bool
val no_overflow_lsl : int -> int -> bool

module Int_literal_converter : sig ... end

val chop_extensions : string -> string
val search_substring : string -> string -> int -> int
val replace_substring : before:string -> after:string -> string -> string
val rev_split_words : string -> string list
val get_ref : 'a list Stdlib.ref -> 'a list
val set_or_ignore : ('a -> 'b option) -> 'b option Stdlib.ref -> 'a -> unit
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

module LongString : sig ... end

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 : Stdlib.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.

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

module Color : sig ... end

module Error_style : sig ... end

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.

val pp_two_columns : ?⁠sep:string -> ?⁠max_lines:int -> Stdlib.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

Hook machinery

Hooks machinery: add_hook name f will register a function that will be called on the argument of a later call to apply_hooks. Hooks are applied in the lexicographical order of their names.

type hook_info = { sourcefile : string; }

exception HookExnWrapper of { error : exn; hook_name : string; hook_info : hook_info; }: An exception raised by a hook will be wrapped into a HookExnWrapper constructor by the hook machinery.

val raise_direct_hook_exn : exn -> 'a: A hook can use raise_unwrapped_hook_exn to raise an exception that will not be wrapped into a HookExnWrapper.

module type HookSig = sig ... end

module MakeHooks : functor (M : sig ... end) -> HookSig with type t = M.t

val show_config_and_exit : unit -> unit: configuration variables

val show_config_variable_and_exit : string -> unit
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.

val print_if : Stdlib.Format.formatter -> bool Stdlib.ref -> (Stdlib.Format.formatter -> 'a -> unit) -> 'a -> 'a: print_if ppf flag fmt x prints x with fmt on ppf if b is true.