Postfix '.' branch now peeks at the next token to disambiguate:
.ident → selector / member access (list :select OBJ "field")
.(TYPE) → type assertion (list :assert OBJ TYPE)
New gp-parse-type covers the minimum types needed for assertions:
name → (list :ty-name "int")
pkg.Name → (list :ty-sel "pkg" "Name")
*T / **T → (list :ty-ptr (list :ty-ptr ...))
Full type grammar — slice []T, array [N]T, map[K]V, chan, func,
struct, interface — is a separate Phase 2 sub-deliverable.
Type AST shapes are Go-specific tagged lists; the canonical AST kit
has no type-system primitives at all yet. Worth a richer kit
discussion once Phase 3 (bidirectional type checker) lands and the
sister plan static-types-bidirectional has a real surface to react to.
parse 70/70, total 199/199.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds the bracket postfix branch:
a[0] / a[i] / a[i+1] / m["key"] → (list :index OBJ IDX)
a[:] / a[1:] / a[:2] / a[1:2] / a[1:2:3] → (list :slice OBJ LOW HIGH MAX)
LOW/HIGH/MAX are AST nodes or nil for omitted indices. The 4th MAX
slot is only populated by the three-index full-slice form.
Two new lib/guest/ast.sx kit gaps surfaced (logged in plans/go-on-sx.md
Blockers):
* No :index node — universal across guests with arrays/maps.
* No :slice node — Python/Rust/Swift/JS/Ruby all need at minimum the
two-index form. Go's three-index variant is more specialised but
fits in the same shape with an optional fourth slot.
Parser is permissive on a[1::3] (strict Go rejects, but the type phase
can enforce the grammar; lexer/parser stays loose).
Chained (a[0][1]) and mixed-with-selector (a[0].field) cases work via
the existing left-associative postfix loop.
parse 61/61, total 190/190.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds postfix expression forms per Go spec:
f() f(x) f(x, y, z) — function calls
x.y x.y.z obj.method(x) — selector / member access
gp-parse-postfix sits between gp-parse-unary and gp-parse-primary,
so calls and selectors bind tighter than any unary prefix — `-f(x)`
parses as `-(f(x))`, not `(-f)(x)`. Postfix is left-associative
(`x.y.z` = `(x.y).z`), so the loop iterates rather than recurses
on the LHS.
AST shapes:
Call: (ast-app FN ARGS) — canonical
Selector: (list :select OBJ "field") — Go-specific tag
The selector shape is a kit gap — lib/guest/ast.sx ships ast-app but
no ast-select, despite `obj.field` being universal across Go, Rust,
Swift, TS, JS, Python, Ruby, Java, C#. Logged in Blockers; tagging
[proposes-ast]. Worth promoting on the next nominally-typed guest.
parse 49/49, total 178/178.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds Go unary prefix operators per Go spec § Operators:
+x -x !x ^x *p &v <-ch
gp-parse-unary is recursive (so !!x and -^x chain correctly) and
sits between gp-parse-expr and gp-parse-primary — unary therefore
always binds tighter than any binary op without needing a unary
entry in the precedence table.
Symbols +, -, *, &, ^ are shared between unary and binary forms;
the positional split (expression-start sees unary, mid-expression
sees binary) disambiguates them cleanly with no lookback.
Unary nodes are single-arg ast-app:
(ast-app (ast-var OP) (list OPERAND))
parse 37/37, total 166/166.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
gp-parse-expr / gp-pratt-loop implement classic Pratt climbing
against go-precedence-table (entry shape from lib/guest/pratt.sx).
The kit gives us pratt-op-lookup + accessors; the climbing loop
itself stays per-language (per kit header — Lua and Prolog have
opposite conventions).
Left-associative ops raise the right-recursion min by 1; right-
associative would keep prec. All Go binary operators are left-assoc.
AST shape: a binary node is emitted as
(ast-app (ast-var OP) [LHS RHS])
— canonical ast-app rather than a Go-specific binary node, since a
future evaluator can recognise operator-named apps without losing
information.
Coverage: equal-prec left-to-right, * tighter than +, && tighter
than ||, comparison tighter than &&, long left-assoc chains, mixed
literal+ident operands.
parse 26/26, total 155/155.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Starts Phase 2. lib/go/parse.sx defines:
* go-precedence-table — Go's five operator-precedence levels in the
(NAME PREC ASSOC) entry shape from lib/guest/pratt.sx, ready for the
binary-operator iteration to consume via pratt-op-lookup.
* go-parse(src) — tokenises and parses ONE primary expression: int,
float, imag, string, rune literals become (ast-literal VALUE);
identifiers become (ast-var NAME). Built directly on lib/guest/ast.sx
constructors — no intermediate AST shape.
Conformance.sh extended to load lib/guest/{ast,pratt}.sx and run the
new parse suite. Scoreboard cleanup: drop the "pending" parse row since
the suite is now real.
parse 17/17 (lex still 129/129). Total 146/146.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
