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22 lines
668 B
Markdown
22 lines
668 B
Markdown
---
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description: Static configuration pieces that affect compilation
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---
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# Overrideable constants
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### `const`
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Constant definition.
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Constants can be used all across functions, exported and imported. If a constant is defined using `?=` , it can be overridden by value via compiler flags or imported values.
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```haskell
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-- This can be overridden with -const "TARGET_PEER_ID = \"other peer id\""
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const TARGET_PEER_ID ?= "this is a target peer id"
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-- This constant cannot be overridden
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const SERVICE_ID = "service id"
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```
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You can assign only literals to constants. Constant type is the same as literal type. You can override only with a subtype of that literal type.
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