1OCAML(1) General Commands Manual OCAML(1)
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6 ocaml - The OCaml interactive toplevel
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10 ocaml [ options ] [ object-files ] [ script-file ]
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13 The ocaml(1) command is the toplevel system for OCaml, that permits
14 interactive use of the OCaml system through a read-eval-print loop. In
15 this mode, the system repeatedly reads OCaml phrases from the input,
16 then typechecks, compiles and evaluates them, then prints the inferred
17 type and result value, if any. The system prints a # (hash) prompt
18 before reading each phrase.
19 A toplevel phrase can span several lines. It is terminated by ;; (a
21 double-semicolon). The syntax of toplevel phrases is as follows.
22 The toplevel system is started by the command ocaml(1). Phrases are
24 read on standard input, results are printed on standard output, errors
25 on standard error. End-of-file on standard input terminates ocaml(1).
26 If one or more object-files (ending in .cmo or .cma) are given, they
28 are loaded silently before starting the toplevel.
29 If a script-file is given, phrases are read silently from the file,
31 errors printed on standard error. ocaml(1) exits after the execution
32 of the last phrase.
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36 The following command-line options are recognized by ocaml(1).
37 -absname
39 Show absolute filenames in error messages.
40 -I directory
42 Add the given directory to the list of directories searched for
43 source and compiled files. By default, the current directory is
44 searched first, then the standard library directory. Directories
45 added with -I are searched after the current directory, in the
46 order in which they were given on the command line, but before
47 the standard library directory.
48 If the given directory starts with +, it is taken relative to
50 the standard library directory. For instance, -I +compiler-libs
51 adds the subdirectory compiler-libs of the standard library to
52 the search path.
53 Directories can also be added to the search path once the
55 toplevel is running with the #directory directive.
56 -init file
58 Load the given file instead of the default initialization file.
59 See the "Initialization file" section below.
60 -labels
62 Labels are not ignored in types, labels may be used in applica‐
63 tions, and labelled parameters can be given in any order. This
64 is the default.
65 -no-app-funct
67 Deactivates the applicative behaviour of functors. With this
68 option, each functor application generates new types in its
69 result and applying the same functor twice to the same argument
70 yields two incompatible structures.
71 -noassert
73 Do not compile assertion checks. Note that the special form
74 assert false is always compiled because it is typed specially.
75 -noinit
77 Do not load any initialization file. See the "Initialization
78 file" section below.
79 -nolabels
81 Ignore non-optional labels in types. Labels cannot be used in
82 applications, and parameter order becomes strict.
83 -noprompt
85 Do not display any prompt when waiting for input.
86 -nopromptcont
88 Do not display the secondary prompt when waiting for continua‐
89 tion lines in multi-line inputs. This should be used e.g. when
90 running ocaml(1) in an emacs(1) window.
91 -nostdlib
93 Do not include the standard library directory in the list of
94 directories searched for source and compiled files.
95 -open module
97 Opens the given module before starting the toplevel. If several
98 -open options are given, they are processed in order, just as if
99 the statements open! module1;; ... open! moduleN;; were input.
100 -plugin plugin
102 Dynamically load the code of the given plugin (a .cmo or .cma
103 file) in the toplevel.
104 -ppx command
106 After parsing, pipe the abstract syntax tree through the pre‐
107 processor command. The module Ast_mapper(3) implements the
108 external interface of a preprocessor.
109 -principal
111 Check information path during type-checking, to make sure that
112 all types are derived in a principal way. When using labelled
113 arguments and/or polymorphic methods, this flag is required to
114 ensure future versions of the compiler will be able to infer
115 types correctly, even if internal algorithms change. All pro‐
116 grams accepted in -principal mode are also accepted in the
117 default mode with equivalent types, but different binary signa‐
118 tures, and this may slow down type checking; yet it is a good
119 idea to use it once before publishing source code.
120 -rectypes
122 Allow arbitrary recursive types during type-checking. By
123 default, only recursive types where the recursion goes through
124 an object type are supported.
125 -safe-string
127 Enforce the separation between types string and bytes, thereby
128 making strings read-only. This will become the default in a
129 future version of OCaml.
130 -short-paths
132 When a type is visible under several module-paths, use the
133 shortest one when printing the type's name in inferred inter‐
134 faces and error and warning messages.
135 -stdin Read the standard input as a script file rather than starting an
137 interactive session.
138 -strict-sequence
140 Force the left-hand part of each sequence to have type unit.
141 -unboxed-types
143 When a type is unboxable (i.e. a record with a single argument
144 or a concrete datatype with a single constructor of one argu‐
145 ment) it will be unboxed unless annotated with [@@ocaml.boxed].
146 -no-unboxed-types
148 When a type is unboxable it will be boxed unless annotated with
149 [@@ocaml.unboxed]. This is the default.
150 -unsafe
152 Turn bound checking off on array and string accesses (the
153 v.(i)ands.[i] constructs). Programs compiled with -unsafe are
154 therefore slightly faster, but unsafe: anything can happen if
155 the program accesses an array or string outside of its bounds.
156 -unsafe-string
158 Identify the types string and bytes, thereby making strings
159 writable. For reasons of backward compatibility, this is the
160 default setting for the moment, but this will change in a future
161 version of OCaml.
162 -version
164 Print version string and exit.
165 -vnum Print short version number and exit.
167 -no-version
169 Do not print the version banner at startup.
170 -w warning-list
172 Enable or disable warnings according to the argument warning-
173 list. See ocamlc(1) for the syntax of the warning-list argu‐
174 ment.
175 -warn-error warning-list
177 Mark as fatal the warnings described by the argument warn‐
178 ing-list. Note that a warning is not triggered (and does not
179 trigger an error) if it is disabled by the -w option. See
180 ocamlc(1) for the syntax of the warning-list argument.
181 -warn-help
183 Show the description of all available warning numbers.
184 - file Use file as a script file name, even when it starts with a
186 hyphen (-).
187 -help or --help
189 Display a short usage summary and exit.
190
193 When ocaml(1) is invoked, it will read phrases from an initialization
194 file before giving control to the user. The default file is .ocamlinit
195 in the current directory if it exists, otherwise .ocamlinit in the
196 user's home directory. You can specify a different initialization file
197 by using the -init file option, and disable initialization files by
198 using the -noinit option.
199 Note that you can also use the #use directive to read phrases from a
201 file.
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205 LC_CTYPE
206 If set to iso_8859_1, accented characters (from the ISO Latin-1
207 character set) in string and character literals are printed as
208 is; otherwise, they are printed as decimal escape sequences.
209 TERM When printing error messages, the toplevel system attempts to
211 underline visually the location of the error. It consults the
212 TERM variable to determines the type of output terminal and look
213 up its capabilities in the terminal database.
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217 ocamlc(1), ocamlopt(1), ocamlrun(1).
218 The OCaml user's manual, chapter "The toplevel system".
219 OCAML(1)