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# The Coq commands¶

There are three Coq commands:

• coqtop: the Coq toplevel (interactive mode);
• coqc: the Coq compiler (batch compilation);
• coqchk: the Coq checker (validation of compiled libraries).

The options are (basically) the same for the first two commands, and roughly described below. You can also look at the man pages of coqtop and coqc for more details.

## Interactive use (coqtop)¶

In the interactive mode, also known as the Coq toplevel, the user can develop his theories and proofs step by step. The Coq toplevel is run by the command coqtop.

There are two different binary images of Coq: the byte-code one and the native-code one (if OCaml provides a native-code compiler for your platform, which is supposed in the following). By default, coqtop executes the native-code version; run coqtop.byte to get the byte-code version.

The byte-code toplevel is based on an OCaml toplevel (to allow dynamic linking of tactics). You can switch to the OCaml toplevel with the command Drop., and come back to the Coq toplevel with the command Coqloop.loop();;.

## Batch compilation (coqc)¶

The coqc command takes a name file as argument. Then it looks for a vernacular file named file.v, and tries to compile it into a file.vo file (See Compiled files).

Caution

The name file should be a regular Coq identifier as defined in Section Lexical conventions. It should contain only letters, digits or underscores (_). For example /bar/foo/toto.v is valid, but /bar/foo/to-to.v is not.

## Customization at launch time¶

Some Coq commands call other Coq commands. In this case, they look for the commands in directory specified by $COQBIN. If this variable is not set, they look for the commands in the executable path. The $COQ_COLORS environment variable can be used to specify the set of colors used by coqtop to highlight its output. It uses the same syntax as the $LS_COLORS variable from GNU’s ls, that is, a colon-separated list of assignments of the form name=attr*; where name is the name of the corresponding highlight tag and each attr is an ANSI escape code. The list of highlight tags can be retrieved with the -list-tags command-line option of coqtop. The string uses ANSI escape codes to represent attributes. For example: export COQ_COLORS=”diff.added=4;48;2;0;0;240:diff.removed=41” sets the highlights for added text in diffs to underlined (the 4) with a background RGB color (0, 0, 240) and for removed text in diffs to a red background. Note that if you specify COQ_COLORS, the predefined attributes are ignored. ### By command line options¶ The following command-line options are recognized by the commands coqc and coqtop, unless stated otherwise: -I directory, -include directory: Add physical path directory to the OCaml loadpath. See also Names of libraries and the command Declare ML Module Section Compiled files. -Q directory dirpath: Add physical path directory to the list of directories where Coq looks for a file and bind it to the logical directory dirpath. The subdirectory structure of directory is recursively available from Coq using absolute names (extending the dirpath prefix) (see Section Qualified names).Note that only those subdirectories and files which obey the lexical conventions of what is an ident are taken into account. Conversely, the underlying file systems or operating systems may be more restrictive than Coq. While Linux’s ext4 file system supports any Coq recursive layout (within the limit of 255 bytes per filename), the default on NTFS (Windows) or HFS+ (MacOS X) file systems is on the contrary to disallow two files differing only in the case in the same directory. See also Section Names of libraries. -R directory dirpath: Do as -Q directory dirpath but make the subdirectory structure of directory recursively visible so that the recursive contents of physical directory is available from Coq using short or partially qualified names. See also Section Names of libraries. -top dirpath: Set the toplevel module name to dirpath instead of Top. Not valid for coqc as the toplevel module name is inferred from the name of the output file. -exclude-dir directory: Exclude any subdirectory named directory while processing options such as -R and -Q. By default, only the conventional version control management directories named CVS and_darcs are excluded. -nois: Start from an empty state instead of loading the Init.Prelude module. -init-file file: Load file as the resource file instead of loading the default resource file from the standard configuration directories. -q: Do not to load the default resource file. -load-ml-source file: Load the OCaml source file file. -load-ml-object file: Load the OCaml object file file. -l file, -load-vernac-source file: Load and execute the Coq script from file.v. -lv file, -load-vernac-source-verbose file: Load and execute the Coq script from file.v. Write its contents to the standard output as it is executed. -load-vernac-object dirpath: Load Coq compiled library dirpath. This is equivalent to runningRequire dirpath. -require dirpath: Load Coq compiled library dirpath and import it. This is equivalent to running Require Import dirpath. -batch: Exit just after argument parsing. Available for coqtop only. -compile file.v: Compile file file.v into file.vo. This option implies -batch (exit just after argument parsing). It is available only for coqtop, as this behavior is the purpose of coqc. -compile-verbose file.v: Same as -compile but also output the content of file.v as it is compiled. -verbose: Output the content of the input file as it is compiled. This option is available for coqc only; it is the counterpart of -compile-verbose. -w (all|none|w₁,…,wₙ): Configure the display of warnings. This option expects all, none or a comma-separated list of warning names or categories (see Section Controlling display). -color (on|off|auto): Coqtop only. Enable or disable color output. Default is auto, meaning color is shown only if the output channel supports ANSI escape sequences. -diffs (on|off|removed): Coqtop only. Controls highlighting of differences between proof steps. on highlights added tokens, removed highlights both added and removed tokens. Requires that –color is enabled. (see Section Showing differences between proof steps). -beautify: Pretty-print each command to file.beautified when compiling file.v, in order to get old-fashioned syntax/definitions/notations. -emacs, -ide-slave: Start a special toplevel to communicate with a specific IDE. -impredicative-set: Change the logical theory of Coq by declaring the sort Set impredicative. Warning This is known to be inconsistent with some standard axioms of classical mathematics such as the functional axiom of choice or the principle of description. -type-in-type: Collapse the universe hierarchy of Coq. Warning This makes the logic inconsistent. -mangle-names ident: Experimental: Do not depend on this option. Replace Coq's auto-generated name scheme with names of the form ident0, ident1, etc. The command Set Mangle Names turns the behavior on in a document, and Set Mangle Names Prefix "ident" changes the used prefix. This feature is intended to be used as a linter for developments that want to be robust to changes in the auto-generated name scheme. The options are provided to facilitate tracking down problems. -compat version: Attempt to maintain some backward-compatibility with a previous version. -dump-glob file: Dump references for global names in file file (to be used by coqdoc, see Documenting Coq files with coqdoc). By default, if file.v is being compiled, file.glob is used. -no-glob: Disable the dumping of references for global names. -image file: Set the binary image to be used by coqc to be file instead of the standard one. Not of general use. -bindir directory: Set the directory containing Coq binaries to be used by coqc. It is equivalent to doing export COQBIN= directory before launching coqc. -where: Print the location of Coq’s standard library and exit. -config: Print the locations of Coq’s binaries, dependencies, and libraries, then exit. -filteropts: Print the list of command line arguments that coqtop has recognized as options and exit. -v: Print Coq’s version and exit. -list-tags: Print the highlight tags known by Coq as well as their currently associated color and exit. -h, --help: Print a short usage and exit. ## Compiled libraries checker (coqchk)¶ The coqchk command takes a list of library paths as argument, described either by their logical name or by their physical filename, hich must end in .vo. The corresponding compiled libraries (.vo files) are searched in the path, recursively processing the libraries they depend on. The content of all these libraries is then type checked. The effect of coqchk is only to return with normal exit code in case of success, and with positive exit code if an error has been found. Error messages are not deemed to help the user understand what is wrong. In the current version, it does not modify the compiled libraries to mark them as successfully checked. Note that non-logical information is not checked. By logical information, we mean the type and optional body associated to names. It excludes for instance anything related to the concrete syntax of objects (customized syntax rules, association between short and long names), implicit arguments, etc. This tool can be used for several purposes. One is to check that a compiled library provided by a third-party has not been forged and that loading it cannot introduce inconsistencies [1]. Another point is to get an even higher level of security. Since coqtop can be extended with custom tactics, possibly ill-typed code, it cannot be guaranteed that the produced compiled libraries are correct. coqchk is a standalone verifier, and thus it cannot be tainted by such malicious code. Command-line options -Q, -R, -where and -impredicative-set are supported by coqchk and have the same meaning as for coqtop. As there is no notion of relative paths in object files -Q and -R have exactly the same meaning. -norec module: Check module but do not check its dependencies. Do not check module and any of its dependencies, unless explicitly required. At exit, print a summary about the context. List the names of all assumptions and variables (constants without body). Do not write progress information to the standard output. Environment variable $COQLIB can be set to override the location of the standard library.

The algorithm for deciding which modules are checked or admitted is the following: assuming that coqchk is called with argument M, option -norec N, and -admit A. Let us write $$\overline{S}$$ for the set of reflexive transitive dependencies of set $$S$$. Then:

• Modules $$C = \overline{M} \backslash \overline{A} \cup M \cup N$$ are loaded and type checked before being added to the context.
• And $$M \cup N \backslash C$$ is the set of modules that are loaded and added to the context without type checking. Basic integrity checks (checksums) are nonetheless performed.

As a rule of thumb, -admit can be used to tell Coq that some libraries have already been checked. So coqchk A B can be split in coqchk A && coqchk B -admit A without type checking any definition twice. Of course, the latter is slightly slower since it makes more disk access. It is also less secure since an attacker might have replaced the compiled library A after it has been read by the first command, but before it has been read by the second command.

 [1] Ill-formed non-logical information might for instance bind Coq.Init.Logic.True to short name False, so apparently False is inhabited, but using fully qualified names, Coq.Init.Logic.False will always refer to the absurd proposition, what we guarantee is that there is no proof of this latter constant.