3 ms·

> FWIW I find this is especially important for compilers and interpreters. Totally. I'm building a relational language and start to get very obvious why RDBMS

by mamcx 6y ago

> FWIW I find this is especially important for compilers and interpreters. Totally. I'm building a relational language and start to get very obvious why RDBMS not fit certain purity ideals of the relational model (like all relations are sets, not bags). I'm stuck in deciding which structures provide by default. Dancing between flat vectors or ndarrays or split between flat vectors (columns), and HashMaps/BTree with n-values (this is my intuition now). --- > I added some nice properties that algebraic data types in some language don't have, e.g. variants are "first class" unlike in Rust. This sound cool, where I can learn about this?

chubot 6y ago
FWIW I found this post thought provoking in thinking about data models of languages. https://news.ycombinator.com/item?id=13293290 https://news.ycombinator.com/item?id=13293290 --- About first class variants: https://lobste.rs/s/77nu3d/oil_s_parser_is_160x_200x_faster_than_it_was#c_gu4oaj https://lobste.rs/s/77nu3d/oil_s_parser_is_160x_200x_faster_... https://github.com/rust-lang/rfcs/pull/2593 https://github.com/rust-lang/rfcs/pull/2593 Another way I think of this is "types vs. tags": https://oilshell.zulipchat.com/#narrow/stream/208950-zephyr-asdl/topic/Better.20solution.3A.20tags.20vs.2E.20types https://oilshell.zulipchat.com/#narrow/stream/208950-zephyr-... (Zulip, requires login) Basically variant can types stand alone, and have a unique tag. Tags are discriminated at RUNTIME with "pattern matching". But a variant can belong to multiple sum types, and that's checked statically. This is modeled with multiple inheritance in OOP, but there's no implementation inheritance. Related: https://pling.jondgoodwin.com/post/when-sum-types-inherit/ https://pling.jondgoodwin.com/post/when-sum-types-inherit/ So basically in the ASDL and C++ and Python type system I can model: - a Token type is a leaf in an arithmetic expression - a Token type is a leaf in an word expression But it's not a leaf in say what goes in a[i], or dozens of other sum types. Shell is a big composition of sublanguages, so this is very useful and natural. Another construct that appears in multiple places is ${x}. So having these invariants modeled by the type system is very useful, and actually C++ and MyPy are surprisingly more expressive than Rust! (due to multiple inheritance) Search for %Token here, the syntax I made up for including a first class variant into a sum type: https://www.oilshell.org/release/0.8.pre9/source-code.wwz/frontend/syntax.asdl https://www.oilshell.org/release/0.8.pre9/source-code.wwz/fr... There is a name for the type, and a name for the tag (and multiple names for the same integer tag). Tags (dynamic) and types (static) are decoupled.

by mamcx 6y ago

chubot 6y ago

FWIW I found this post thought provoking in thinking about data models of languages. https://news.ycombinator.com/item?id=13293290 https://news.ycombinator.com/item?id=13293290 --- About first class variants: https://lobste.rs/s/77nu3d/oil_s_parser_is_160x_200x_faster_than_it_was#c_gu4oaj https://lobste.rs/s/77nu3d/oil_s_parser_is_160x_200x_faster_... https://github.com/rust-lang/rfcs/pull/2593 https://github.com/rust-lang/rfcs/pull/2593 Another way I think of this is "types vs. tags": https://oilshell.zulipchat.com/#narrow/stream/208950-zephyr-asdl/topic/Better.20solution.3A.20tags.20vs.2E.20types https://oilshell.zulipchat.com/#narrow/stream/208950-zephyr-... (Zulip, requires login) Basically variant can types stand alone, and have a unique tag. Tags are discriminated at RUNTIME with "pattern matching". But a variant can belong to multiple sum types, and that's checked statically. This is modeled with multiple inheritance in OOP, but there's no implementation inheritance. Related: https://pling.jondgoodwin.com/post/when-sum-types-inherit/ https://pling.jondgoodwin.com/post/when-sum-types-inherit/ So basically in the ASDL and C++ and Python type system I can model: - a Token type is a leaf in an arithmetic expression - a Token type is a leaf in an word expression But it's not a leaf in say what goes in a[i], or dozens of other sum types. Shell is a big composition of sublanguages, so this is very useful and natural. Another construct that appears in multiple places is ${x}. So having these invariants modeled by the type system is very useful, and actually C++ and MyPy are surprisingly more expressive than Rust! (due to multiple inheritance) Search for %Token here, the syntax I made up for including a first class variant into a sum type: https://www.oilshell.org/release/0.8.pre9/source-code.wwz/frontend/syntax.asdl https://www.oilshell.org/release/0.8.pre9/source-code.wwz/fr... There is a name for the type, and a name for the tag (and multiple names for the same integer tag). Tags (dynamic) and types (static) are decoupled.