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This was discussed and agreed in #246. It will probably break a few outstanding PRs as well as a few external links but it's for the better good long term.
64 lines
1.3 KiB
Markdown
64 lines
1.3 KiB
Markdown
# Declarative vs imperative
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- Our container orchestrator puts a very strong emphasis on being *declarative*
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- Declarative:
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*I would like a cup of tea.*
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- Imperative:
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*Boil some water. Pour it in a teapot. Add tea leaves. Steep for a while. Serve in a cup.*
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--
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- Declarative seems simpler at first ...
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--
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- ... As long as you know how to brew tea
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---
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## Declarative vs imperative
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- What declarative would really be:
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*I want a cup of tea, obtained by pouring an infusion¹ of tea leaves in a cup.*
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--
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*¹An infusion is obtained by letting the object steep a few minutes in hot² water.*
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--
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*²Hot liquid is obtained by pouring it in an appropriate container³ and setting it on a stove.*
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--
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*³Ah, finally, containers! Something we know about. Let's get to work, shall we?*
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--
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.footnote[Did you know there was an [ISO standard](https://en.wikipedia.org/wiki/ISO_3103)
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specifying how to brew tea?]
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---
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## Declarative vs imperative
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- Imperative systems:
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- simpler
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- if a task is interrupted, we have to restart from scratch
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- Declarative systems:
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- if a task is interrupted (or if we show up to the party half-way through),
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we can figure out what's missing and do only what's necessary
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- we need to be able to *observe* the system
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- ... and compute a "diff" between *what we have* and *what we want*
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