FutureLearn Erlang - My first erlang program

first.erl

-module(first).
-export([add/2, double/1, mult/2, area/3, treble/1, square/1]).

add(A,B) ->
    A + B.

mult(X,Y) ->
    X * Y.

double(X) ->
    mult(2, X).

treble(X) ->
    mult(3, X).

area(A,B,C) ->
    S = (A + B + C) / 2,
    math:sqrt(S*(S-A)*(S-B)*(S-C)).

square(X) ->
    mult(X,X).

second.erl

-module(second).
-import(first, [square/1, add/2, mult/2]).
-export([hypothenus/2, area_from_sides/2, perimeter_from_sides/2]).

hypothenus(A,B) ->
    square(A) + square(B).

area_from_sides(A,B) ->
    mult(A,B) / 2.

perimeter_from_sides(A,B) ->
    add(A,B) + (math:sqrt(hypothenus(A,B))).

This is perfect, but I would recommend not to use -import and just write things like first:square(…) and such.

This is perfect, but I would recommend not to use -import and just write things like first:square(…) and such.

Thanks! I think with the right IDE support this is not a problem, you can always go to definition.
At least in theory, I didn't manage on mine :( (vim-erlang-runtime)

Yeah… but you can't easily copy&paste code in a console to test it and debug it… which is something that, I promise you, you'll be doing a lot.