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0 pointscatnaroek9y ago0 comments

> Funny, but that's exactly what we Smalltalkers had in Smalltalk

Smalltalk doesn't let you say “this object responds to message Foo only when used in this part of the program”. In other words, there's no separation of concerns.

> and almost all of it in our heads

What you realistically can't produce entirely in your head is a proof that your program is correct, unless the language is explicitly designed to lift part of this proof obligation. That's exactly the role of parametricity: to help you separate concerns, allowing you to prove one small thing at a time.

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stcredzero9y ago

Smalltalk doesn't let you say “this object responds to message Foo only when used in this part of the program”.

In VisualWorks, there were different two ways of writing a short script to verify this in a matter of seconds. You could also sometimes achieve this with a few cascaded searches through the Refactoring Browser.

catnaroekOP9y ago

> In VisualWorks, there were different two ways of writing a short script to verify this in a matter of seconds.

This doesn't scale to either large programs or programs not entirely written by yourself.

In ML, there's no need to search anything: the only admissible operations on a value are those sanctioned by its type.

> You could also sometimes achieve this with a few cascaded searches through the Refactoring Browser.

As a library author, you can't search code written by users of your library.

In ML, I can prove things not only about my own code, but also about how others may use it.

stcredzero9y ago

This doesn't scale to either large programs or programs not entirely written by yourself.

My industry experience clearly shows that you're just flat wrong -- with multiple large systems written by other people over the span of over a decade.

As a library author, you can't search code written by users of your library.

What kind of nonsense is this? The library author doesn't need to do such a search! The library users in Smalltalk would do such searches. Access to source was the norm. Decompilation in Smalltalk is trivially perfect, excluding local variable names, so closed source was fairly pointless.

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0 pointscatnaroek9y ago0 comments

> Funny, but that's exactly what we Smalltalkers had in Smalltalk

Smalltalk doesn't let you say “this object responds to message Foo only when used in this part of the program”. In other words, there's no separation of concerns.

> and almost all of it in our heads

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stcredzero9y ago

Smalltalk doesn't let you say “this object responds to message Foo only when used in this part of the program”.

catnaroekOP9y ago

> In VisualWorks, there were different two ways of writing a short script to verify this in a matter of seconds.

This doesn't scale to either large programs or programs not entirely written by yourself.

In ML, there's no need to search anything: the only admissible operations on a value are those sanctioned by its type.

> You could also sometimes achieve this with a few cascaded searches through the Refactoring Browser.

As a library author, you can't search code written by users of your library.

In ML, I can prove things not only about my own code, but also about how others may use it.

stcredzero9y ago

This doesn't scale to either large programs or programs not entirely written by yourself.

My industry experience clearly shows that you're just flat wrong -- with multiple large systems written by other people over the span of over a decade.

As a library author, you can't search code written by users of your library.

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