[plt-scheme] Why this code based on SRFI-42 does not work under PLT Scheme ?

[Bruno Carnazzi]

   Hi folks,

I'd like to know why this code does not work under PLT Scheme :

(require srfi/42)

(first-ec #f (: n 0 100)  (if (even? n)) n)

It fails with message :

:until: expected <generator> in  in: (if (even? n))


Best regards,

Bruno.

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