Danila Fedorin
f23705a93e
Introduce [spa_e| ... ] for Expr and [spa| ... ] for Stmt, scoped to the Spa namespace via a dedicated syntax category and macro_rules. This removes the deeply nested .andThen / .basic (.assign ...) boilerplate when writing programs; Main.lean's test programs are rewritten to use it. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
61 lines
2.1 KiB
Lean4
61 lines
2.1 KiB
Lean4
import Spa.Language.Base
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namespace Spa
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/-!
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Scoped quotation syntax for writing object-language programs.
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`[obj_expr| … ]` builds an `Expr`, `[obj_stmt| … ]` builds a `Stmt`.
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Example:
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```
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[obj_stmt|
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zero := 0;
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pos := zero + 1;
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if pos { x := 1 } else { noop };
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while x { x := x - 1 }
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]
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```
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-/
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/-- Expressions of the object language. -/
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declare_syntax_cat obj_expr
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syntax num : obj_expr
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syntax ident : obj_expr
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syntax:65 obj_expr:65 " + " obj_expr:66 : obj_expr
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syntax:65 obj_expr:65 " - " obj_expr:66 : obj_expr
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syntax "(" obj_expr ")" : obj_expr
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/-- Statements of the object language. -/
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declare_syntax_cat obj_stmt
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syntax "noop" : obj_stmt
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syntax ident " := " obj_expr : obj_stmt
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syntax "if " obj_expr " { " obj_stmt " } " "else" " { " obj_stmt " } " : obj_stmt
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syntax "while " obj_expr " { " obj_stmt " } " : obj_stmt
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syntax:50 obj_stmt:51 "; " obj_stmt:50 : obj_stmt
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syntax "(" obj_stmt ")" : obj_stmt
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scoped syntax "[obj_expr| " obj_expr " ]" : term
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scoped syntax "[obj_stmt| " obj_stmt " ]" : term
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scoped macro_rules
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| `([obj_expr| $n:num]) => `(Expr.num $n)
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| `([obj_expr| $x:ident]) => `(Expr.var $(Lean.quote x.getId.toString))
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| `([obj_expr| $a + $b]) => `(Expr.add [obj_expr| $a] [obj_expr| $b])
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| `([obj_expr| $a - $b]) => `(Expr.sub [obj_expr| $a] [obj_expr| $b])
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| `([obj_expr| ($e:obj_expr)]) => `([obj_expr| $e])
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scoped macro_rules
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| `([obj_stmt| noop]) => `(Stmt.basic .noop)
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| `([obj_stmt| $x:ident := $e]) =>
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`(Stmt.basic (.assign $(Lean.quote x.getId.toString) [obj_expr| $e]))
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| `([obj_stmt| $s₁ ; $s₂]) => `(Stmt.andThen [obj_stmt| $s₁] [obj_stmt| $s₂])
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| `([obj_stmt| if $e { $s₁ } else { $s₂ }]) =>
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`(Stmt.ifElse [obj_expr| $e] [obj_stmt| $s₁] [obj_stmt| $s₂])
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| `([obj_stmt| while $e { $s }]) => `(Stmt.whileLoop [obj_expr| $e] [obj_stmt| $s])
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| `([obj_stmt| ($s:obj_stmt)]) => `([obj_stmt| $s])
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end Spa
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