# Suggestion: Fortran-like Keyword to Assert Function is Pure

**URL:** <https://discourse.julialang.org/t/suggestion-fortran-like-keyword-to-assert-function-is-pure/63047>\
**Category:** Internals & Design\
**Created:** [June 16, 2021, 8:34pm UTC](https://discourse.julialang.org/t/suggestion-fortran-like-keyword-to-assert-function-is-pure/63047 "2021-06-16T20:34:37Z")\
**Posts on this page:** 1\
**Showing post:** 32

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**Author:** ![StefanKarpinski](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stefankarpinski/32/24_2.png) [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)\
**Post date:** [June 18, 2021, 4:04pm UTC](https://discourse.julialang.org/t/suggestion-fortran-like-keyword-to-assert-function-is-pure/63047/32 "2021-06-18T16:04:53Z")

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Sorry, I know this litany of questions is annoying, but they are why this sort of thing isn’t so simple. It’s much more reasonable in Fortran since it is a static language with a separate type checking and compilation phase which is a natural time for the purity checking to happen. It is also a language without multimethods or dynamic dispatch, so any time a function call occurs, there is only one statically knowable function that can be called.

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