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; What color is your function?
; Impure functions are functions that can call both pure and impure functions.
; Pure functions can only call pure functions.
; Impure function names end in an exclamation mark (!) by convention.
; The top-level context is impure but has special rules
; related to `import`, `let`, and other builtins.
; this is a pure function
(let f (\[x] x))
(f 10) ; works
; this is an impure function
(let g! (\![x] (println! x)))
(g! "foo") ; works
; this is a pure function that tries to call an impure function
(let h (\[x] (g! x)))
(h "bar")
; error: cannot call impure function in pure context
; when calling function g! at examples/purity-test.milch:19:15
; in a function definition at examples/purity-test.milch:19:12
; when calling function h at examples/purity-test.milch:21:1
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