Why is lambda calculus not used much (in general)?

Question

Why is pure untyped lambda calculus often described as impossible to use?

With a suitable library of functions, will it not be about the same as any other functional language?

Answer 1

In theory, theory and practice are the same. In practice, this is not so.

In theory, it will be just another functional language. But have you considered the effect of performance on the actual performance of mathematics with Church numbers? Yes you can do it. But your programs will run so slowly that they will look seriously broken. A practical, functional language should find ways to make a pragmatic compromise between providing abstractions that can be built and using fast, native implementations of commonly used things.

Answer 2

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