Orkuncakilkaya
ab0b84b87e
An action names one row of a ludic.base Table<T> by its handle, in a field marked @Target, and `reducer Deer in Herd.deer on Spook(r: mut Row<Deer>, n: Noise, a: Spook)` runs once, for that row alone (the table may sit down a path, S.w.tab). The drain resolves the handle (tb_row) and hands the reducer a Row<T> - new in ludic.base: tb, row, h, rec - that the queue keeps, one per row reducer, filled in place, so a targeted action allocates nothing; a stale handle runs nothing, and LUDIC_ACTIONS_LOG=1 prints a line for it (@alloc_ok). Row reducers order among an action's by their state's name, then the table's path. Checked at compile time (actions_rows.ludic): the row reaches r.rec and r.h only - r.tb / r.row refused, the view never assigned, stored, copied or handed on except to a @RowVerb (a function of the record's own module taking Row<T> first; any other function taking a row is refused); a field marked @Column (a table column mirrors it) is not written through r.rec; only the module owning the state declares a row reducer; one @Target, an int, per action; the states between the row and the action are read. `mut` is allowed on a Row<T> parameter. ludic schema's code section gains row_reducers (record, table, state, action, target, predicted, net, module, at) and row_verbs (name, record, module, at), and every action its target; row reducers are left out of `reducers`. ludic deps and ludic-lsp name a row reducer `reducer Deer in Herd.deer on Spook`. vocab: @Target, @Column, @RowVerb; docs/language pages; LANGUAGE.md "A reducer on a row"; examples actions/rows and ten rejects; test.ludic feat, reject and schema cases (not run); changes/row-reducers.md. Reseeded; bootstrap-cfree fixpoint holds (307497 lines); Maroon Lake's `ludic build --check` is clean against this tree. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
29 lines
1.3 KiB
Markdown
29 lines
1.3 KiB
Markdown
---
|
|
id: kw-reducer
|
|
name: reducer
|
|
category: structure
|
|
kind: keyword
|
|
tokens: reducer
|
|
sig: reducer State on Action(st: mut State, reads..., a: Action) { ... } / reducer Record in State.table on Action(r: mut Row<Record>, reads..., a: Action) { ... }
|
|
tip: Applies an action to one state, or to the one table row its @Target names; it may read others.
|
|
order: 62
|
|
---
|
|
|
|
A <code>reducer</code> writes exactly one state when its action is dispatched: the first parameter is that state, <code>mut</code>, the last is the action, and any states between are read-only. A change that must touch several states in a set order is a chain: a reducer dispatches the next action.
|
|
|
|
```ludic
|
|
state Pos { x: int = 0 }
|
|
action Move { dx: int = 0 }
|
|
reducer Pos on Move(p: mut Pos, a: Move) {
|
|
p.x = p.x + a.dx
|
|
}
|
|
```
|
|
|
|
Written <code>in State.table</code>, a reducer runs for the one row of that <code>Table<Record></code> the action's <code>@Target</code> field names: it is handed a <code>Row<Record></code>, reaches <code>r.rec</code> and <code>r.h</code>, and changes a field a column mirrors (<code>@Column</code>) only through a <code>@RowVerb</code>. A handle whose row is gone runs nothing.
|
|
|
|
```ludic
|
|
# doc-check: skip — needs ludic.base's Table
|
|
reducer Deer in Herd.deer on Spook(r: mut Row<Deer>, a: Spook) {
|
|
r.rec.fear += a.by
|
|
}
|
|
```
|