mrange

// ----------------------------------------------------------------------------------------------
// Copyright 2017 Mårten Rånge
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
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//     http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software

mrange

F# Advent 2016 (English) - December 10 - Implementing a persistent hash map.

This blog created for F# Advent 2016 (English)

Full source code can be found here

Changelog

1. 2016-12-10
2. New performance test - Anthony Lloyd (@AnthonyLloyd) suggested that I compare against Prime.Vmap.

mrange

On the topic of data locality and performance

Full source code can be found here

It is well-known that a hard disk has a long delay from that we request the data to that we get the data. Usually we measure the hard disk latency in milliseconds which is an eternity for a CPU. The bandwidth of a hard disk is decent good as SSD:s today can reach 1 GiB/second.

What is less known is that RAM has the same characteristics, bad latency with good bandwidth.

You can measure RAM latency and badndwidth using Intel® Memory Latency Checker. On my machine the RAM latency under semi-high load is ~120 ns (The 3r:1w bandwidth is 16GiB/second). This means that the CPU on my machine has to wait for ~400 cycles for data, an eternity.

CRogers

module FParsecTrace

open FParsec
open FParsec.Primitives
open FParsec.CharParsers

open System.Text

type DebugInfo = { Message: string; Indent: int }
type UserState = { mutable Debug: DebugInfo }

hindol

(defn ws-listener
  [_request _response ws-map]
  (proxy [WebSocketAdapter] []
    (onWebSocketConnect [^Session ws-session]
      (proxy-super onWebSocketConnect ws-session)
      (when-let [f (:on-connect ws-map)]
        (f ws-session)))
    (onWebSocketClose [status-code reason]
      (when-let [f (:on-close ws-map)]
        (f (.getSession this) status-code reason)))

swlkr

(ns switch
  (:require [clojure.pprint :as pprint]))

(defn project-clj-map [filename]
  (->> (slurp filename)
       (read-string)
       (drop 1)
       (partition 2)
       (map vec)
       (into {})))

swannodette

(ns async-test.timeout.core
  (:require [cljs.core.async :refer [chan close!]])
  (:require-macros
    [cljs.core.async.macros :as m :refer [go]]))
 
(defn timeout [ms]
  (let [c (chan)]
    (js/setTimeout (fn [] (close! c)) ms)
    c))
 

madskristensen

//********************************************************//

// HOW TO:
// Create a file called devenv.pkgundef in the same directory as devenv.exe. 
// It's usually located at C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE
// Then call "devenv.exe /updateconfiguration" from an elevated command prompt.

// REMARKS:
// Each GUID below represent a package that Visual Studio is loading. This is the
// list of package that I personally don't ever use. You can modify the list of

mrange

On the topic of tail calls in .NET

Let's say you have implemented a small data pipeline library to replace LINQ.

module TrivialStream =
  type Receiver<'T> = 'T            -> unit
  type Stream<'T>   = Receiver<'T>  -> unit

  module Details =

halgari

(ns scratch)

(defn map [f]
  (fn [xf]
    (fn
      ([] (xf))
      ([acc] (xf acc))
      ([acc itm]
       (xf acc (f itm))))))