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First day with PureScript

Mar 5, 2016

After installation & run purs init, bower install purescript-node-http I tried to undestand what’s going on.

My idea was to start node.js http server using standard http module in the simplest form.

After few fails, I copied the example from purescript-node-http repo.

After fixing some warnings it got run.

So I removed all but bare minimum which gave code as below:

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module Main where

import Prelude

import Node.HTTP
import Node.Stream
import Node.Encoding

import Data.Foldable (foldMap)

import Control.Monad.Eff.Console

main = do
  server <- createServer respond
  listen server 8080 $ void do  
    log "Server is listening!"
  where
  respond req res = do          
    log "Incoming request"

And to test it we’ll use curl:

  • on first terminal - pulp run
  • on second terminal - curl :8080

And the result is - displaying “Incoming request”!

Main finding of the day:

  • line 14 - call createServer and provide respond callback. Assigns it to server which is const, because I heard that all data is const in PureScript. Maybe I’m wrong.

log just logs on console :)

Question of the day:

What the f… are those $ and = do - line 15

Bonus question:

What is void - line 15

Code can be found at this GitHub tag.