Genspio is a typed EDSL to generate shell scripts and commands from OCaml.
The idea is to build values of type
'a EDSL.t with the
combinators in the
Genspio.EDSL module, and compile them to POSIX
shell scripts (or one-liners) with functions from
See the file
which generates a useful list of usage examples, or the
section “Getting Started” below.
The tests run the output of the compiler against a few shells that it tries to
find on the host (e.g.
zsh … cf. the
example test results summary below).
If you have any questions, do not hesitate to submit an
Genspio's documentation root is at https://smondet.gitlab.io/genspio-doc/.
You can install the library though
opam install genspio
Or get the development version with
opam pin add genspio https://github.com/hammerlab/genspio.git
You can also build locally:
ocaml please.mlt configure jbuilder build @install
Here is a quick example:
utop> open Genspio.EDSL;; utop> let c = let username_one_way : str t = (* We lift the string "USER" to EDSL-land and use function `getenv`: *) getenv (str "USER") in let username_the_other_way : str t = (* The shell-pipe operator is `||>` *) (exec ["whoami"] ||> exec ["tr"; "-d"; "\\n"]) (* `get_stdout` takes `stdout` from a `unit t` as a `byte_array t` *) |> get_stdout in let my_printf : string -> str t list -> unit t = fun fmt args -> (* The function `call` is like `exec` but operates on `str t` values instead of just OCaml strings: *) call (str "printf" :: str fmt :: args) in (* The operator `=$=` is `str t` equality, it returns a `bool t` that we can use with `if_seq`: *) if_seq Str.(username_one_way =$= username_the_other_way) ~t:[ my_printf "Username matches: `%s`\\n" [username_one_way]; ] ~e:[ my_printf "Usernames do not match: `%s` Vs `%s`\\n" [username_one_way; username_the_other_way]; ] ;; val c : unit t utop> Sys.command (Genspio.Compile.to_one_liner c);; Username matches: `smondet` - : int = 0
Genspio.EDSLprovides the Embedded Domain Specific Language API to build
shell script expressions (there is also a lower-level, not recommended,
Genspio.Compilehas the 3 “compilers” provided by the library:
The pretty printer outputs
'a EDSL.tvalues as expressions of a
The default “
To_posix” compiler generates POSIX-compliant shell
scripts (with the option of avoiding new-lines).
⤷ Note that MacOSX's default
bashversion is buggy and has been
witnessed to choke on generated POSIX-valid scripts.
The newer “
To_slow_flow” compiler generates POSIX shell scripts which
are much simpler, hence more portable across shell implementations, but
use (a lot of) temporary files and are generally slower.
Genspio.Transformimplements code transformations:
Visitorprovides an extensible AST visitor.
Constant_propagationdoes some basic constant propagation
(using the visitor).
There are many examples in
which are used to generate the usage examples documentation webpage.
contains another big example: a script that downloads and unpacks archives
is a “Makefile + scripts” generator to setup Qemu virtual machines, they can
be for instance used to run the tests on more exotic platforms.
hammerlab/secotrecis a real-world,
larger-scale use of Genspio (uses Genspio version 0.0.0).
From here, one can explore:
Some implementation notes.
More information on testing, e.g. on more exotic
Genspio.EDSL_v0is an older version of the API, which can still
be useful as it is lower-level: it gives full access to the two “string-like”
types, byte-arrays and C-strings while of course becoming more cumbersome to
To run the tests you also need
make and there is an additional dependency on
uri library, see:
genspio_test=_build/default/src/test/main.exe jbuilder build $genspio_test $genspio_test --help
$genspio_test --important-shells bash,dash /tmp/gtests/ cd /tmp/gtests/ make run-all # Attempts to run all the tests on all the shells make check # Checks that all the tests for the important ones succeeded
You can generate a markdown report with
make report and check
You can check failures in the
<shell-test>/failures.md files, see for instance
ksh-StdML/failures.md for the failures of the “KSH with standard Genspio
compilation to multi-line scripts” (similarly there are
Building The Documentation
To build the documentation one needs
It's Apache 2.0.