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Brandon Weaver baweaver

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View pattern_match_hash_array.rb
case { it: { works: { on: 1, nested: 'hashes' }, cool: true } }
in it: { works: { on: Integer, nested: String }, cool: TrueClass }
# => true
case [{ that: { includes: [:this, :too] }}, { more: 'splats'}, {see?: true}]
in [{ that: { includes: Array } }, *]
baweaver /
Created Nov 24, 2019
Current WIP of pattern matching documentation. Still needs more work.

Pattern Matching

Pattern match statements are an extension of the case expression. They introduce a new keyword to case statements: in.

The in expression

in is used in place of when to use pattern matching behaviors. These two syntaxes cannot be mixed.

An in expression is different from when in that it allows one to match against data structures:

baweaver / symbol_ap.rb
Created Oct 19, 2019
Stealing some vague ideas from Applicatives in Haskell, probably wrongly but it amuses me so...
View symbol_ap.rb
class Symbol
def ap(*applied_args)
-> *block_args {
if applied_args.empty?
receiver, *new_args = block_args[0]
receiver.send(self, *new_args)
else*block_args, *applied_args)
baweaver / favorite_things_ruby_edition
Last active Sep 21, 2019
A Few of my Favorite Things translated to Ruby (WIP)
View favorite_things_ruby_edition
Ruby programming
And Gems pushed to GitHub
Cloud based deployments and CI / CD
Tests that will pass on the first try
These are a few of my favorite things
Just Rails new app name
and omakase thinking
convention o'er configuration
and sane default settings
View hash_set_extension.rb
class Hash
alias_method :+, :merge
def -(other)
other_keys =
# Irrelevant value method
# reject { |k, _v| other_keys.include?(k) }
# Relevant value method
View proposed_pipeline.rb
def double(n) n * 2 end
increment = -> n { n + 1 }
|> double # Method
|> increment # Proc
|> to_s(2) # self.to_s

Tales of the Ruby Grimoire


The council of 3.0 had been called, and Scarlet was readying to join them to discuss the future of the land of Ruby. With her was her student, Red, carrying out his latest lesson.

"Now be sure to finish the remaining problems by the time I return, Red. I expect I'll have many fun things to tell you of when I return." said Scarlet.

Red nodded, still writing away on his scrolls, but as Scarlet exited the castle a sly sort of grin grew on his face.

View contramap.rb
class Proc
def contramap(&fn) self << fn end
adds = -> a, b { a + b }.curry
[1, 2, 3].map(&adds[2])
# => [3, 4, 5]
# What if the type on the left doesn't work with `adds`?
baweaver / async_helpers.js
Created Apr 12, 2019
Helpers for working with ActionCable async on the client side
View async_helpers.js
// Helpers
const MAX_WAIT = 10000;
const POLLING_RATE = 500;
export function timedOut (maxWait) {
const startTime =;
return () => - startTime > maxWait;
baweaver /
Created Jan 26, 2019
Raw notes from my TracePoint session


What is TracePoint?

A class that provides the functionality of Kernel#set_trace_func in a nice Object-Oriented API.

Well what is set_trace_func?

Establishes proc as the handler for tracing, or disables tracing if the parameter is nil.

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