Effect Functor / Reader Monad

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Effect Functor / Reader Monad

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Last edited Jan 9, 2019

Created on Jan 9, 2019

This example demonstrates functional programming patterns—an Effect functor and Reader monad—as JavaScript objects with methods like `map`, `chain`, `join`, and `ap`. The Effect wraps an impure function like `fZero`, while `Effect.of` creates a pure initial value. The Reader monad, using `Reader.ask`, threads a shared environment (a database and logger) through a composed `updateTask` pipeline. The code simulates a database update and logging by explicitly invoking `run` with those dependencies, showing how side effects are deferred and composed without direct state mutation.

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