How should we design the elm-in-elm command line interface? I suggest that the design should provide
A pure interface
At the core of the design should be a command that is as pure as possible.
The compiler takes some (elm) files and produces some (javascript) files.
Given the same input files the compiler produces the same output files.
This command should not try to connect to the internet, read the elm.json file or try to fetch packages from a cache.
All the input files (including packages) that it needs must be provided as arguments to the command [1].
A high level command
Using a low level compiler CLI directly quickly gets cumbersome and users reach for higher level commands to build actual software.
Traditionally, these higher level commands execute the lower level command as a sub-process.
It may be preferable for elm-in-elm to use the library version of the lower level command rather than executing the command directly.
This command can read the elm.json file, fetch the necessary packages, compile them [2]
and pass them to the lower level command.
Support for common work-flows
We could support common/encouraged work-flows by providing bespoke commands. For example, a test command that builds and runs all the tests for an application or package supports test driven work-flows. To flesh out how these extra commands would interact with each other, I think it worth considering a test command even if an implementation of such a command is a long way off.
My draft
Threfore, a starting point for the CLI is three sub-commands. The following are draft man pages:
$ elm-in-elm --help
A compiler for elm, written in elm.
USAGE:
elm-in-elm [OPTIONS] [SUBCOMMAND]
OPTIONS:
-V, --version Print version info and exit
--list List installed commands
-h, --help Prints help information
Some common elm-in-elm commands are (see all commands with --list):
compile Compile an elm file
build Build an elm application or library
test Run the tests
See 'elm-in-elm help <command>' for more information on a specific command.
$ elm-in-elm help compile
Compile an elm file.
Usage: elm-in-elm compile [OPTIONS] INPUT
Options:
-h, --help Display this message
-L PATH Add a directory to the library search path.
-l NAME Link the generated crate(s) to the specified native
library NAME.
--emit Comma separated list of types of output for the
compiler to emit. One of js or ast.
-o FILENAME Write output to <filename>
--target TARGET Target triple for which the code is compiled
-V, --version Print version info and exit
-v, --verbose Use verbose output
Additional help:
--help -v Print the full set of options elm-in-elm compile accepts
$ elm-in-elm help build
Build an elm application or package.
Usage: elm-in-elm build [OPTIONS]
Options:
-h, --help Display this message
--example <NAME>... Build the specified example
--test <NAME>... Build the specified test target
--release Build artifacts in release mode, with optimizations
--target <TRIPLE> Build for the target triple
-V, --version Print version info and exit
-v, --verbose Use verbose output
-h, --help Prints help information
$ elm-in-elm help test
Execute all tests.
Usage: elm-in-elm test [OPTIONS]
Options:
-h, --help Display this message
--example <NAME>... Test only the specified example
--test <NAME>... Test only the specified test target
--target <TRIPLE> Build for the target triple
-V, --version Print version info and exit
-v, --verbose Use verbose output
-h, --help Prints help informationHarry.
gcc main.c -lcurl to compile your c program whilst linking the libcurl.a library (installed using sudo apt install libcurl4-openssl-dev).