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Eager evaluation

Eager evaluation is an execution strategy that computes expressions or performs operations immediately rather than deferring them until their results are needed.

How 5 Manning books explain it

Deep Learning with R, Third Edition

Eager execution is an execution mode in which operations run immediately and produce results without first constructing a deferred computation graph.

How it is used
Runs TensorFlow, PyTorch, and JAX operations immediately to support interactive development and straightforward debugging.
How deep it goes
Explains immediate execution, debugging benefits, and performance costs, then contrasts eager operation with compilation.
Examples
Uses TensorFlow tensor operations and nested gradient tapes, plus PyTorch linear models and training steps, as concrete eager examples.
What you can do after
Diagnose/debug tensor code interactively, then choose whether TensorFlow or PyTorch compilation is worth its performance and reliability costs.

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Functional Programming in Scala, Second Edition

Strict code evaluates an argument or expression before the surrounding computation proceeds, rather than delaying evaluation until its value is needed.

How it is used
Contrasts default strict computation with nonstrict techniques for controlling when expressions are evaluated.
How deep it goes
Defines strict argument evaluation and demonstrates its timing, but defers broader implementation details to nonstrictness and laziness.
Examples
Uses square, sys.error, conditional branches, short-circuiting operators, and LazyList construction to expose evaluation timing.
What you can do after
Evaluate Scala calls by predicting which arguments run before function bodies and which expressions can be skipped.

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Deep Learning with PyTorch, Second Edition

An execution model in which operations run immediately rather than being first built into a static graph.

How it is used
Runs PyTorch operations immediately throughout model development, training, evaluation, and deployment workflows.
How deep it goes
Explains execution through the Python interpreter and C++ or CUDA backends, while deferring detailed deployment capabilities to later treatment.
Examples
Uses PyTorch tensor instructions and a project flow spanning data loading, training, model export, and deployment.
What you can do after
Apply it via PyTorch by reasoning about each tensor operation as it executes and by relating computation to deployment choices.

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Functional Programming in JavaScript

How it is used
Explains why JavaScript may perform unnecessary work before a dependent operation can limit the result.
How deep it goes
Defines immediate expression evaluation and contrasts it with deferred execution, without detailing language-runtime internals.
Examples
Uses range with take, a Maybe fallback, conditional control flow, and a Lodash map-filter-take chain.
What you can do after
Apply conditional control flow or Lodash shortcut fusion to avoid unnecessary function calls and large intermediate results.

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Fast Python: High performance techniques for large datasets

How it is used
Contrasts immediate pandas and NumPy computation with deferred Dask execution and frames choices as performance trade-offs.
How deep it goes
Explains execution timing, memory, wasted work, repeated traversal, and measured performance, but does not detail runtime internals.
Examples
Uses range timing, generator-based temperature parsing, list conversion, and a Dask property-tax computation.
What you can do after
Evaluate eager and lazy alternatives using memory considerations, workload needs, and IPython timing measurements.

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Related concepts

These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.