Create gleam-for-go-users guide #321
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This is an initial version that is mostly a copy of gleam-for-php-users.md
Made a lot of progress...
| In Gleam, `let` and `=` can be used for pattern matching, but you'll get | ||
| compile errors if there's a type mismatch, and a runtime error if there's | ||
| a value mismatch. For assertions, the equivalent `let assert` keyword is | ||
| preferred. |
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It's not just preferred! It's enforced. Could you rework to make it clear that let won't cause a runtime error.
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Want to make this clear, if I have a value from Erlang that does not match the interface put on that code, and I do a let with pattern that does not match that value it does not cause a runtime error?
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The compiler won't let you match a let pattern if it doesn't match all possible cases. let assert will cause a runtime error if the pattern doesn't match
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@gamebox are you planning on updating this PR? |
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Yes, sorry I missed Louis's comments. I'll update sometime this week.
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cheatsheets/gleam-for-go-users.md
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| In Go, you can choose to not export a type and then they will be considered | ||
| opaque to the user of your package. Just have the type have a lowercase | ||
| identifier. |
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It will be opaque from outside the package, which is the same thing as private? I might be misunderstanding
This will save some editing work, before I address the meatier comments. Co-authored-by: Louis Pilfold <[email protected]>
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This should be ready for your review when you get a chance @lpil |
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I'd really love to close this out, if you get a chance @lpil . |
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isn't it better to use the equivalent/similar example in the Unions section? |
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@MiniAppleTheApple Well, there really isn't a similar approach unless you mean a struct that has a tag and then contains pointers to structs for all possible "variants" or contains all of the fields relevant to all variants. But I personally think it's more honest to say "This really isn't a thing you would do in Go". Plus, union semantics are just different then either of the two options I described above. |
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All conversations are resolved, and suggestions merged. Looks like now this should be good for a final review. |
Even though there isn't a 100% similar way, you can still approximate both example code as close as possible. I will give a suggestion later. |
| - [Unions](#unions) IN PROGRESS | ||
| - [Opaque custom types](#opaque-custom-types) IN PROGRESS | ||
| - [Modules](#modules) IN PROGRESS | ||
| - [Imports](#imports) IN PROGRESS | ||
| - [Named imports](#named-imports) IN PROGRESS | ||
| - [Unqualified imports](#unqualified-imports) IN PROGRESS | ||
| - [Architecture](#architecture) IN PROGRESS |
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Are these actually "in progress"? Or should this note be removed?
| - Go is an imperative programming language, with only very limited object-oriented facilities | ||
| provided. Gleam offers only functional code style, though it can appear | ||
| imperative and reads easily thanks to pipes. | ||
| - In Gleam, data structures are never mutated but always updated into new | ||
| structures. This allows processes that fail to simply restart as there are no | ||
| mutated objects that can be in an invalid state and take the whole | ||
| application down (such as in languages like Ruby or Go). | ||
| - Gleam offers syntax to make it easy to extract data out of custom types and | ||
| update data into new copies of custom types without ever mutating variables. | ||
| Go sometimes directly mutates references of simple values such as when using | ||
| pointers or global variables, though this is very much not idiomatic. | ||
| - Gleam allows to rebind variables freely to make it easy to update data | ||
| structures by making a copy and binding it to the existing variable. | ||
| - Go features a massive, powerful standard library centered around simple interfaces. |
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These aren't really dot points, but paragraphs.
I would:
- Remove the dot points
- Move the last paragraph to the second paragraph so the Go and Gleam paragraphs are kept together
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| To iterate a few foundational differences (Go VS Gleam): | ||
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| 1. Programming model: imperative VS functional immutable |
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A common Go-ism is something like:
- Declare struct
- Declare constructor
- Declare methods on struct
It would be handy to see how you'd achieve this in Gleam.
I know that for Gleam some people recommend a "context" struct that you pass in as the first argument which contains what would normally be Go struct fields: Database connections, loggers, HTTP clients etc.
This is a first draft and needs some editing and fact checking.
Closes #413