If Scheme is untyped, how can it have numbers and lists?

Posted by Dokkat on Programmers See other posts from Programmers or by Dokkat
Published on 2014-05-29T20:11:43Z Indexed on 2014/05/29 21:56 UTC
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Filed under:

type-systems

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Scheme

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lambda

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racket

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lambda-calculus

Scheme is said to be just an extension of the Untyped Lambda Calculus (correct me if I am wrong). If that is the case, how can it have Lists and Numbers? Those, to me, look like 2 base types. So I'd say Racket is actually an extension of the Simply Typed Lambda Calculus. No?

Question:

Is Scheme's type system actually based or more similar to Simply Typed or Untyped Lambda Calculus?
In what ways does it differ from Untyped and or Simply Typed Lambda Calculus?

(The same question is valid for "untyped" languages such as Python and JavaScript - all of which look like they have base types to me.)

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