alid ~main

Introduction

This repository is a collection of D modules written by Ali Çehreli.

Name

The package name alid is a combination of "Ali" and "D".

History

It started with cached which was based on an old idea of Ali's that rested for more than ten years. Ali decided to revisit the idea when a piece of D code--written by Janis, a friend and colleague--produced surprising results. The surprises were due to side effects in a generator function similar to the map lambda in the following code:

    auto r = iota(n)
             .map!((i) {
                     arr ~= i;     // <-- A side effect (adds to an array)
                     return i;
                 })
             .filter!(i => true);  // <-- The side effect is repeated

Every access to the generated "element" down the execution chain repeats the side effect, adding one more element to the array in the code above.

Features

cached

cached is for executing elements only once while not holding on to old elements for too long; the elements that have been popFronted by all ranges are dropped from the cache according some heuristics.

cached was the main topic of Ali's DConf 2022 lightning talk.

It caches the elements of its source range to ensure that the side effect of each generated element is applied only once:

    auto r = iota(n)
             .map!((i) {
                     arr ~= i;     // <-- A side effect (adds to an array)
                     return i;
                 })
             .cached               // <-- Caches the generated elements
             .filter!(i => true);  // <-- The side effect is NOT repeated

cached provides a ForwardRange interface as well as random access to elements even when the source range is an InputRange.

circularblocks

circularblocks was written for storing range elements of cached. It can be used independently.

blockreusable

blockreusable was written as storage blocks for circularblocks. It can be used independently.

errornogc

errornogc was needed for throwing Errors from @nogc code. It can be used independently.

test

test contains some helper utilities for unit testing.