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Now, there are two local binders: let x = ... use x = ... The 'let' binder will create a local definition, type-check it, and assign a name to it. When compiled, it will create 'dup' nodes. The 'use' binder is just an alias. It will not bind a new variable, and, when compiled, will create inline copies. Also, for type-checking, it allows creating aliases that are definitionaly equal for the checker.
13 lines
353 B
Plaintext
13 lines
353 B
Plaintext
List.find
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: ∀(A: *) ∀(cond: ∀(x: A) Bool) ∀(list: (List A))
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(Maybe A)
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= λA λcond λlist
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use P = λx (Maybe A)
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use cons = λhead λtail
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use found = (cond head)
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use P = λx (Maybe A)
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use true = (Maybe.some A head)
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use false = (List.find A cond tail)
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(~found P true false)
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use nil = (Maybe.none A)
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(~list P cons nil) |