maiha

• https://github.com/crystal-lang/crystal/blob/0.20.4/CHANGELOG.md

maiha

module Core
end

class Base(T)
  include Core
end

class Foo < Base(String)
end

maiha

• https://github.com/maiha/try.cr Try
• https://github.com/dry-cr/dry-monads Maybe, Either
• https://github.com/jdantonio/edge.cr Either, Maybe, Optional
• https://github.com/dhruvrajvanshi/crystal-futures Future

maiha

def parse(str)
  JSON.parse(str)
end

pp parse("1") # => 1
pp parse("x") # raise JSON::ParseException

begin
  v = parse("1")
  # use v

maiha

module Core(T)
  @a : Bool
end

class Base(T)
  include Core(Int32)

  def initialize
    @a = true
  end

maiha

class Changeset(T)
  def initialize(@instance : T)
  end
end

module Cset(T)
  def changeset(instance)
    Changeset(T).new(instance)
  end
end

maiha

#!/usr/bin/env zsh
set -e

# for shards-0.7
rm -rf shard.lock libs
shards update
echo "/lib/" >> .gitignore

# MemoryIO
sed -i "s/MemoryIO/IO::Memory/g" {src,spec}/**/*.cr

maiha

% git clone [email protected]:crystal-lang/crystal_lib.git
% cd crystal_lib
% cat > lib_ntohl.cr
@[Include("arpa/inet.h")]
lib LibC
  fun ntohl
end

% crystal src/main.cr -- lib_ntohl.cr
lib LibC

maiha

alias Entry = Hash(Symbol, File::Stat | String)

def awalkDir(dir, block : Entry -> Nil)

  Dir.entries(dir).each do |fname|
    next if fname == "."  || fname == ".."

    current = File.join(dir, fname)

    begin

maiha

127.0.0.1:6379> zadd zset 100 a
(integer) 1
127.0.0.1:6379> zadd zset 200 b
(integer) 1
127.0.0.1:6379> eval "return {redis.call('ZSCORE',KEYS[1],KEYS[2]),redis.call('ZRANK',KEYS[1],KEYS[2])}" 2 zset b
1) "200"
2) (integer) 1

127.0.0.1:6379> script load "return {redis.call('ZSCORE',KEYS[1],KEYS[2]),redis.call('ZRANK',KEYS[1],KEYS[2])}"
"b6b9e64ed4cc349469e0f24c49469c6d6fcdfc5a"