Pythonicity

GraphQL root fields

There is no such thing as a “root field”.

graphql

There is a common - seemingly universal - misconception that GraphQL root fields are somehow special, in both usage and implementation. The better conceptual model is that…

Composition vs. inheritance

Contrarian view on composition over inheritance.

style

The conventional wisdom is to prefer composition over inheritance. More specifically to use delegation over single inheritance.

Decorator overuse

Decorators versus blocks and partial functions.

style

Decorators are a beloved feature of Python, but like any good thing can be overused. The key is acknowledging that decorators are just functions.

GraphQL nulls

Litany against nulls.

graphql

The myths and misconceptions regarding null behavior in GraphQL are epic. Even the spec is wrong.

GraphQL coroutines

GraphQL resolvers should have been coroutines.

graphql

This is how the GraphQL documentation introduces execution, as a hierarchy of resolvers:

Random Selection

Generate random numbers efficiently.

interviews

Random selection utilities used to be common in interviews. Less so in Python circles because of the builtin random module. Still advanced examples may come up. First is a…

Primes

Generate prime numbers.

interviews

An old interview challenge is to generate prime numbers or check if a number is prime. No advanced mathematics needed, just variants on the Sieve of Eratosthenes. Starting…

Hardest Logic Puzzle Ever

How to solve the Hardest Logic Puzzle Ever programmatically.

puzzles

Three gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or…

GraphQL - ORM

GraphQL is the new ORM.

graphql

REST and ORMs are both infamous for:

Closing files

Contrarian view on closing files.

style

It has become conventional wisdom to always explicitly close file-like objects, via context managers. The google style guide is representative:

Mutable defaults

Contrarian view on mutable default arguments.

style

The use of mutable defaults is probably the most infamous Python gotcha. Default values are evaluated at definition time, which means mutating them will be persistent across…

Water pouring

How to solve the water pouring puzzle programmatically.

puzzles

Given two jugs of capcity of 3 and 5 liters, acquire exactly 4 liters in a jug. Assume an unlimited water supply, and that jugs can only be filled or emptied, i.e., no…

Coin balance

How to solve the coin balance puzzle programmatically.

puzzles

Given a balance and a set of coins, which are all equal in weight except for one, determine which coin is of different weight in as few weighings as possible.

Hat puzzle

How to solve the Hat puzzle programmatically.

puzzles

Ten-Hat Variant

Split an Iterable

Split an iterable into equal sized chunks.

interviews

A common task and interview question, with many variants. It’s frequently asked and answered in a way that’s suboptimal and only handles one specific case. The goal here is…

Accumulator

A Paul Graham classic, the accumulator function.

style

As an illustration of what I mean about the relative power of programming languages, consider the following problem. We want to write a function that generates accumulators–…

Map and Filter

Contrarian view on map and filter.

style

Although PEP 8 is silent on the topic, it’s become recommended in many Python circles to eschew map and filter in favor of generator expressions or list comprehensions. For…

Fizz Buzz

The infamously simple FizzBuzz problem.

interviews

Reportedly a high percentage of programmer applicants can’t solve this quickly.

Cheryl’s Birthday

How to solve the Cheryl’s Birthday puzzle programmatically.

puzzles

As with the pytudes solution, the goal is to solve the puzzle in code. A different approach is taken here though, for simplicity and extensibility.