Ecl

Ecl helps to run your Erlang code without making a lot of preparations. It also can make your code a command line tool.

Usage

Consider a simple example. Imagine you want to write a function that reverses a list, but do not want to write anything except the algorithm itself. Also you want to have a command line tool from your code installed into the system.

Code

Let's name our project "rev" and edit a module file for it:

$ make edit rev

This opens "vi" with a file of the following content:

-module(ecl_rev).
-export([run/1]).

run(Arg) -> Arg.

We can already run this code. Let's save and close the file and run it:

$ make run rev [1,2,3,4,5]
[1,2,3,4,5]

Well, that did nothing with our list as expected, so let's do the actual job. Edit the file again:

$ make edit rev

and modify it by adding the reversing code:

-module(ecl_rev).
-export([run/1]).

run(Arg) -> lists:reverse(Arg).

Save and run again:

$ make run rev [1,2,3,4,5]
[5,4,3,2,1]

We are done.

Hint

You can see how changes affect the output continuously. In one window run:

watch make run rev [1,2,3,4,5]

and edit your code in another one.

Command line tool

Having the command line tool of our code in the system as simple as:

$ make install

Now we can run our "reverse" anywhere pretty much the same way:

$ ecl rev [1,2,3,4,5]
[5,4,3,2,1]

Just "ecl" instead of "make run".

Uninstall command line tool

To uninstall:

$ make uninstall

More examples

Mutiply each element of a list by a specified factor.

$ make edit listx

-module(ecl_listx).
-export([run/2]). % you need to change this line from the default "run/1"

run(List, Factor) -> [X * Factor || X <- List].

$ make run listx [1,2,3,4,5] 3
[3,6,9,12,15]

Subcommand.

$ make edit arith

-module(ecl_arith).
-export([run/3]). % you need to change this line from the default "run/1"

run(add, A, B) -> A + B;
run(mult, A, B) -> A * B.

$ make run arith add 3 5
8
$ make run arith mult 3 5
15