Can this FizzBuzz example be made more of an exemplar of LFE?

[Steven Proctor]

I am going to be giving a little lightning talk at work about Erlang, as part of a "Hello World!" languages presentation, and one of the requirements of the talk is to show FizzBuzz in the language we are going to be talking about.

Some of the people at work thought Elixir would be interesting to show, so I thought I would try to make the presentation more about the Erlang VM than Erlang specifically, and with that I wanted to include FizzBuzz done in LFE.

Here is the solution I came up with, and I wanted to check with the list if this is the way you all would write it.

This feels very Erlang-ish centric, with just using parens, so any feedback on style, or using some built in LFE functions/macros instead of just calling the standard Erlang functions, or anything else that would help make it more illustrative of LFE.  

(defmodule fizzbuzz

 (export (fizzbuzz 1)))

(defun fizzbuzz (n)

  (lists:foreach

    (lambda (x) (io:format "~p~n" (list x)))

    (lists:map

      (lambda (x) (translate_number x))

      (lists:seq 1 n))))

(defun translate_number

  ((n) (when (and (== 0 (rem n 3))

                  (== 0 (rem n 5))))

    "FizzBuzz")

  ((n) (when (== 0 (rem n 3)))

    "Fizz")

  ((n) (when (== 0 (rem n 5)))

    "Buzz")

  ((n) n))

Thank you all for your feedback!!!

And Duncan, before you ask, yes, I can write this up as a blog post for blog.lfe.io, and I will even include my learnings from any feedback given about how to make this more LFE. ;)

--Proctor

[Eric]

Have you seen examples/fizzbuzz.lfe in the LFE repo?

In this gist I’ve stripped out the commentary, modernized the syntax, capitalized on the fact that in LFE (and Erlang), functions with the same name but different arities are considered distinct, and made sure it matches your code logic-wise. It also uses quasiquoting for the format form, i.e. `(,x) instead of (list x).

One style point about your code is that translate_number should be translate-number, since dashes are preferred to underscores.

Cheers,

Eric

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[Robert Virding]

Three quick points:

- There is an lfe_io module for writing things out with LFE syntax

- If you just want the words Fizz and Buzz without quotes have then as atom (haven't read the actual problem)

- Strings are self quoting so there is no need to quote them.

Robert

[Eric]

On Aug 16, 2015, at 8:46 PM, Robert Virding <rvir...@gmail.com> wrote:

Three quick points:

- There is an lfe_io module for writing things out with LFE syntax

- If you just want the words Fizz and Buzz without quotes have then as atom (haven't read the actual problem)

- Strings are self quoting so there is no need to quote them.

I didn’t know that, cool!

> (=:= "a string" '"a string")

true

I’ve updated the gist too. It now uses atoms and lfe_io.

[Duncan McGreggor]

Woo-hoo!

Can't wait to publish it :-D

d

[Steven Proctor]

Robert, Eric,

Thanks for your feedback and info.

Here is an updated solution that takes into account the feedback.  In addition to that I also introduced a let binding form to show off that aspect of the Lisp in LFE.

(defmodule fizzbuzz

 (export (fizzbuzz 1)))

(defun fizzbuzz (n)

  (lists:foreach

    #'write-line/1

    (translate-upto n)))

(defun translate-upto (n)

  (let ((numbers (lists:seq 1 n)))

    (lists:map

      #'translate/1

      numbers)))

(defun write-line

  ((string) (lfe_io:format "~p~n" `(,string))))

(defun translate

  ((n) (translate n (rem n 3) (rem n 5))))

(defun translate

  ([_ 0 0] 'FizzBuzz)

  ([_ 0 _] 'Fizz)

  ([_ _ 0] 'Buzz)

  ([n _ _] n))

I will be presenting it on Wednesday, so I will be putting the final touches on the presentation tomorrow night, so if you see something else that should be updated, I am all ears.

--Proctor

Robert

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[Duncan McGreggor]

Quick question below:

On Mon, Aug 17, 2015 at 11:27 PM, Steven Proctor <steven....@gmail.com> wrote:

Robert, Eric,

Thanks for your feedback and info.

Here is an updated solution that takes into account the feedback.  In addition to that I also introduced a let binding form to show off that aspect of the Lisp in LFE.

(defmodule fizzbuzz

 (export (fizzbuzz 1)))

(defun fizzbuzz (n)

  (lists:foreach

    #'write-line/1

    (translate-upto n)))

(defun translate-upto (n)

  (let ((numbers (lists:seq 1 n)))

    (lists:map

      #'translate/1

      numbers)))

(defun write-line

  ((string) (lfe_io:format "~p~n" `(,string))))

(defun translate

  ((n) (translate n (rem n 3) (rem n 5))))

For both of those last two functions, they each do no matching... is there are reason you didn't write them like this?

(defun write-line (string)

  (lfe_io:format "~p~n" `(,string)))

(defun translate (n)

  (translate n (rem n 3) (rem n 5)))

 

Did they used to be part of a multi-clause function whose parts were later removed?

Just curious,

d

Robert

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[Eric Bailey]

I like your showcasing of let and the #'f/a syntax. Also +1 to Duncan's edits.

I'm excited for the blog post and to hear how LFE is received at your work.

Sent from my iPhone

[Steven Proctor]

Thanks for catching that!

Was just lack of experience in actually writing LFE for any length of time, which I am slowly trying to address. ;)

--Proctor

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