go: lex.sx — decimal float + imaginary literals + 22 tests [consumes-lex]

Adds Go float and imaginary literal forms per Go spec § Floating-point
literals and § Imaginary literals:
  3.14   .5   1.   1e10   1.5e-3   2.0e+2   1E5    (floats)
  2i     3.14i   1e2i                              (imag)

gl-read-number! returns one of "int" / "float" / "imag"; gl-finish-number!
factors out the post-mantissa exponent + 'i' suffix logic so the int /
float / leading-dot-float paths all share it. scan! adds a .<digit>
branch ahead of the operator matcher so '.5' tokenises as float.

ASI trigger list extended to include float + imag (Go spec § Semicolons:
all literal types trigger).

Greedy-grammar pin (a single test '1.method' lexes as float ident),
since the Go spec says the '.' after a digit always belongs to the
number, never to a following identifier.

Hex floats (0x1.fp0) deferred — not commonly used.

lex 114/114.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/go/lex.sx

@@ -8,6 +8,8 @@
 ;;   "keyword" — one of the 25 Go keywords
 ;;   "int"     — integer literals (decimal, 0x.. hex, 0b.. binary, 0o.. octal,
 ;;               legacy 0123 octal; underscores between digits allowed)
+;;   "float"   — decimal float literals (3.14, .5, 1., 1e10, 1.5e-3, 1E5)
+;;   "imag"    — imaginary literals (2i, 3.14i, 1e2i)
 ;;   "string"  — interpreted string literals "..."
 ;;   "rune"    — rune literals 'x' (single char + simple escapes)
 ;;   "op"      — operators & punctuation; :value is the literal text
@@ -16,7 +18,7 @@
 ;;
 ;; ASI (Go spec § Semicolons): a newline (or EOF, or a block comment
 ;; containing a newline) emits a ";semi" if the previous emitted token's
-;; type is ident/int/string/rune, or its value is one of
+;; type is ident/int/float/imag/string/rune, or its value is one of
 ;;   {break, continue, fallthrough, return, ++, --, ), ], }}.
 ;;
 ;; All scanner locals are gl- prefixed: SX host primitives (peek/emit/etc.)
@@ -57,6 +59,8 @@
 
 (define go-asi-ops (list "++" "--" ")" "]" "}"))
 
+(define go-asi-lit-types (list "ident" "int" "float" "imag" "string" "rune"))
+
 (define
   go-asi-trigger?
   (fn
@@ -67,10 +71,7 @@
       (let
         ((ty (get tok :type)) (v (get tok :value)))
         (or
-          (= ty "ident")
+          (some (fn (lt) (= lt ty)) go-asi-lit-types)
-          (= ty "int")
-          (= ty "string")
-          (= ty "rune")
           (and (= ty "keyword") (some (fn (k) (= k v)) go-asi-keywords))
           (and (= ty "op") (some (fn (o) (= o v)) go-asi-ops)))))))
 
@@ -143,30 +144,70 @@
             (and (< pos src-len) (or (digit? (gl-cur)) (= (gl-cur) "_")))
             (gl-advance! 1)
             (gl-read-digit-run! digit?))))
+      (define
+        gl-finish-number!
+        (fn
+          (has-fraction?)
+          (let
+            ((typ (if has-fraction? "float" "int")))
+            (when
+              (or (= (gl-cur) "e") (= (gl-cur) "E"))
+              (gl-advance! 1)
+              (when
+                (or (= (gl-cur) "+") (= (gl-cur) "-"))
+                (gl-advance! 1))
+              (gl-read-digit-run! lex-digit?)
+              (set! typ "float"))
+            (cond
+              (= (gl-cur) "i")
+              (do (gl-advance! 1) "imag")
+              :else typ))))
       (define
         gl-read-number!
         (fn
           ()
           (cond
+            (and (= (gl-cur) ".") (lex-digit? (gl-peek 1)))
+            (do
+              (gl-advance! 1)
+              (gl-read-digit-run! lex-digit?)
+              (gl-finish-number! true))
             (and
               (= (gl-cur) "0")
               (or
                 (= (gl-peek 1) "x")
                 (= (gl-peek 1) "X")))
-            (do (gl-advance! 2) (gl-read-digit-run! lex-hex-digit?))
+            (do
+              (gl-advance! 2)
+              (gl-read-digit-run! lex-hex-digit?)
+              "int")
             (and
               (= (gl-cur) "0")
               (or
                 (= (gl-peek 1) "b")
                 (= (gl-peek 1) "B")))
-            (do (gl-advance! 2) (gl-read-digit-run! gl-bin-digit?))
+            (do
+              (gl-advance! 2)
+              (gl-read-digit-run! gl-bin-digit?)
+              "int")
             (and
               (= (gl-cur) "0")
               (or
                 (= (gl-peek 1) "o")
                 (= (gl-peek 1) "O")))
-            (do (gl-advance! 2) (gl-read-digit-run! gl-oct-digit?))
+            (do
-            :else (gl-read-digit-run! lex-digit?))))
+              (gl-advance! 2)
+              (gl-read-digit-run! gl-oct-digit?)
+              "int")
+            :else (do
+              (gl-read-digit-run! lex-digit?)
+              (cond
+                (and (= (gl-cur) ".") (not (= (gl-peek 1) ".")))
+                (do
+                  (gl-advance! 1)
+                  (gl-read-digit-run! lex-digit?)
+                  (gl-finish-number! true))
+                :else (gl-finish-number! false))))))
       (define
         gl-read-string!
         (fn
@@ -371,9 +412,14 @@
             (lex-digit? (gl-cur))
             (do
               (let
-                ((start pos))
+                ((start pos) (typ (gl-read-number!)))
-                (gl-read-number!)
+                (gl-emit! typ (slice src start pos) start))
-                (gl-emit! "int" (slice src start pos) start))
+              (gl-scan!))
+            (and (= (gl-cur) ".") (lex-digit? (gl-peek 1)))
+            (do
+              (let
+                ((start pos) (typ (gl-read-number!)))
+                (gl-emit! typ (slice src start pos) start))
               (gl-scan!))
             (= (gl-cur) "\"")
             (let

lib/go/scoreboard.json

@@ -1,9 +1,9 @@
 {
   "language": "go",
-  "total_pass": 92,
+  "total_pass": 114,
-  "total": 92,
+  "total": 114,
   "suites": [
-    {"name":"lex","pass":92,"total":92,"status":"ok"},
+    {"name":"lex","pass":114,"total":114,"status":"ok"},
     {"name":"parse","pass":0,"total":0,"status":"pending"},
     {"name":"types","pass":0,"total":0,"status":"pending"},
     {"name":"eval","pass":0,"total":0,"status":"pending"},

lib/go/scoreboard.md

@@ -1,10 +1,10 @@
 # Go-on-SX Scoreboard
 
-**Total: 92 / 92 tests passing**
+**Total: 114 / 114 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
-| ✅ | lex | 92 | 92 |
+| ✅ | lex | 114 | 114 |
 | ⬜ | parse | 0 | 0 |
 | ⬜ | types | 0 | 0 |
 | ⬜ | eval | 0 | 0 |

lib/go/tests/lex.sx

@@ -74,7 +74,7 @@
 (go-test "int: bigger" (tok-values "123456") (list "123456" "\n" nil))
 (go-test "int: type" (tok-types "42") (list "int" "semi" "eof"))
 
-;; ── integer literals — prefixed + underscores (Go spec § Integer literals)
+;; ── integer literals — prefixed + underscores ─────────────────────
 (go-test "int: hex lower" (tok-values "0x1f") (list "0x1f" "\n" nil))
 (go-test "int: hex upper-x" (tok-values "0X1F") (list "0X1F" "\n" nil))
 (go-test
@@ -105,6 +105,43 @@
   (tok-types "0xFF + 1")
   (list "int" "op" "int" "semi" "eof"))
 
+;; ── float literals (Go spec § Floating-point literals) ────────────
+(go-test "float: simple" (tok-values "3.14") (list "3.14" "\n" nil))
+(go-test "float: trailing dot" (tok-values "1.") (list "1." "\n" nil))
+(go-test "float: leading dot" (tok-values ".5") (list ".5" "\n" nil))
+(go-test "float: exp lower" (tok-values "1e10") (list "1e10" "\n" nil))
+(go-test "float: exp upper" (tok-values "1E5") (list "1E5" "\n" nil))
+(go-test "float: exp negative" (tok-values "1.5e-3") (list "1.5e-3" "\n" nil))
+(go-test "float: exp positive" (tok-values "2.0e+2") (list "2.0e+2" "\n" nil))
+(go-test "float: zero" (tok-values "0.0") (list "0.0" "\n" nil))
+(go-test "float: dot-only-exp" (tok-values ".5e2") (list ".5e2" "\n" nil))
+(go-test "float: underscore" (tok-values "1_000.5") (list "1_000.5" "\n" nil))
+(go-test "float: type" (tok-types "3.14") (list "float" "semi" "eof"))
+(go-test
+  "float: trailing dot type"
+  (tok-types "1.")
+  (list "float" "semi" "eof"))
+(go-test
+  "float: exp-only type"
+  (tok-types "1e10")
+  (list "float" "semi" "eof"))
+(go-test
+  "float: then +"
+  (tok-types "3.14 + 0.1")
+  (list "float" "op" "float" "semi" "eof"))
+(go-test
+  "float: greedy 1.method"
+  (tok-types "1.method")
+  (list "float" "ident" "semi" "eof"))
+
+;; ── imaginary literals (Go spec § Imaginary literals) ─────────────
+(go-test "imag: int i" (tok-values "2i") (list "2i" "\n" nil))
+(go-test "imag: float i" (tok-values "3.14i") (list "3.14i" "\n" nil))
+(go-test "imag: exp i" (tok-values "1e2i") (list "1e2i" "\n" nil))
+(go-test "imag: int-i type" (tok-types "2i") (list "imag" "semi" "eof"))
+(go-test "imag: float-i type" (tok-types "3.14i") (list "imag" "semi" "eof"))
+(go-test "imag: ASI at newline" (tok-types "1i\n") (list "imag" "semi" "eof"))
+
 ;; ── string literals ───────────────────────────────────────────────
 (go-test "string: empty" (tok-values "\"\"") (list "" "\n" nil))
 (go-test "string: hello" (tok-values "\"hello\"") (list "hello" "\n" nil))
@@ -170,6 +207,7 @@
   (tok-types "x\ny")
   (list "ident" "semi" "ident" "semi" "eof"))
 (go-test "ASI: after int" (tok-types "42\n") (list "int" "semi" "eof"))
+(go-test "ASI: after float" (tok-types "3.14\n") (list "float" "semi" "eof"))
 (go-test
   "ASI: after string"
   (tok-types "\"hi\"\n")

plans/go-on-sx.md

@@ -141,12 +141,13 @@ Progress-log line → push `origin/loops/go`.
 - [x] **Automatic semicolon insertion** (Go spec § Semicolons) — newline,
       EOF, and block-comment-with-newline trigger `;` after
       ident/int/string/rune/{break,continue,fallthrough,return}/{++,--,),],}}.
-- [ ] Float / imaginary literals
+- [x] Float / imaginary literals (decimal floats: `3.14 .5 1. 1e10 1.5e-3`;
+      imag: `2i 3.14i 1e2i`; hex floats `0x1.fp0` deferred)
 - [ ] Raw string literals `` `...` ``
 - [x] Hex/octal/binary integer literals (0x… 0o… 0b…) + underscores
       (legacy 0123 octal also accepted; consumes lex-hex-digit?)
 - [ ] Full operator set audit (47 distinct per Go spec)
-- **Acceptance:** lex/ suite at 50+ tests. Current: 92/92.
+- **Acceptance:** lex/ suite at 50+ tests. Current: 114/114.
 
 ### Phase 2 — Parser (`lib/go/parse.sx`) ⬜
 - Consume `lib/guest/core/pratt.sx` + `lib/guest/core/ast.sx`. Chisel notes
@@ -405,6 +406,12 @@ _(none yet)_
 
 _Newest first. Append one dated entry per commit._
 
+- 2026-05-27 — Phase 1 cont.: decimal float + imaginary literals.
+  `3.14`, `.5`, `1.`, `1e10`, `1.5e-3`, `2i`, `3.14i`. `gl-finish-number!`
+  handles exponent + `i` suffix; `gl-read-number!` returns the type
+  string (int/float/imag). ASI trigger list extended to float/imag.
+  Greedy-grammar pin: `1.method` lexes as `float ident`. Hex floats
+  (`0x1.fp0`) deferred. +22 tests, lex 114/114. `[consumes-lex]`.
 - 2026-05-27 — Phase 1 cont.: prefixed integer literals (`0x..`, `0X..`,
   `0b..`, `0B..`, `0o..`, `0O..`, legacy `0123`) + underscore separators
   in any digit run. Dispatch in `gl-read-number!`; consumes