start simple examples

examples/simple-ruby/Gemfile

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+source 'https://rubygems.org'
+
+ruby '>= 3.0'
+
+gem 'sqlite3', '~> 2.0', '>= 2.0.1'
+gem 'sqlite-vec'

examples/simple-ruby/Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    sqlite-vec (0.0.1.alpha.3-x86_64-darwin)
+    sqlite3 (2.0.1-x86_64-darwin)
+
+PLATFORMS
+  x86_64-darwin-21
+
+DEPENDENCIES
+  sqlite-vec
+  sqlite3 (~> 2.0, >= 2.0.1)
+
+RUBY VERSION
+   ruby 3.2.2p53
+
+BUNDLED WITH
+   2.4.10

examples/simple-ruby/demo.rb

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+require 'sqlite3'
+require 'sqlite_vec'
+
+
+db = SQLite3::Database.new(':memory:')
+db.enable_load_extension(true)
+SqliteVec.load(db)
+db.enable_load_extension(false)
+
+sqlite_version, vec_version = db.execute("select sqlite_version(), vec_version()").first
+puts "sqlite_version=#{sqlite_version}, vec_version=#{vec_version}"
+
+db.execute("CREATE VIRTUAL TABLE vec_items USING vec0(embedding float[8])")
+
+items = [
+  [1, [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8]],
+  [2, [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8]]
+]
+db.transaction do
+  items.each do |item|
+    db.execute("INSERT INTO vec_items(rowid, embedding) VALUES (?, ?)", [item[0], item[1].pack("f*")])
+  end
+end
+
+query = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8]
+rows = db.execute(<<-SQL, [query.pack("f*")])
+  SELECT
+    rowid,
+    distance
+  FROM vec_items
+  WHERE embedding MATCH ?
+  ORDER BY distance
+  LIMIT 5
+SQL
+
+puts rows