From 1f19cba76f547648ea97f51f2c78a76f2ad2c315 Mon Sep 17 00:00:00 2001
From: Dag Brattli <dag@brattli.net>
Date: Sun, 18 Oct 2026 22:48:47 +0200
Subject: [PATCH] feat: add Erlang binary and number predicates

---
 src/otp/Erlang.fs  |  8 ++++++++
 test/TestErlang.fs | 29 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/otp/Erlang.fs b/src/otp/Erlang.fs
index 7d28995..152fee0 100644
--- a/src/otp/Erlang.fs
+++ b/src/otp/Erlang.fs
@@ -138,6 +138,14 @@ let exactEquals (a: 'T) (b: 'T) : bool = nativeOnly
 [<Emit("erlang:is_list($0)")>]
 let isList (term: 'T) : bool = nativeOnly
 
+/// Returns true if Term is an Erlang binary (a bitstring of whole bytes).
+[<Emit("erlang:is_binary($0)")>]
+let isBinary (term: 'T) : bool = nativeOnly
+
+/// Returns true if Term is an Erlang integer or float, without converting it.
+[<Emit("erlang:is_number($0)")>]
+let isNumber (term: 'T) : bool = nativeOnly
+
 // ============================================================================
 // Time
 // ============================================================================
diff --git a/test/TestErlang.fs b/test/TestErlang.fs
index d1f0355..80036f3 100644
--- a/test/TestErlang.fs
+++ b/test/TestErlang.fs
@@ -40,6 +40,35 @@ let tests =
                     assertThat (Erlang.exactEquals ref1 ref1) (isTrue)
             )
 
+            test (
+                "isBinary accepts binaries and rejects other terms",
+                fun _ ->
+                    assertThat (Erlang.isBinary "hello") (isTrue)
+                    assertThat (Erlang.isBinary "") (isTrue)
+                    assertThat (Erlang.isBinary 42) (isFalse)
+                    assertThat (Erlang.isBinary (Atom.ofString "hello")) (isFalse)
+
+                    let charlist: Dynamic = emitErlExpr () "[104, 101, 108, 108, 111]"
+                    let partialByte: Dynamic = emitErlExpr () "<<7:12>>"
+                    assertThat (Erlang.isBinary charlist) (isFalse)
+                    assertThat (Erlang.isBinary partialByte) (isFalse)
+            )
+
+            test (
+                "isNumber accepts integers and floats without accepting other terms",
+                fun _ ->
+                    assertThat (Erlang.isNumber 42) (isTrue)
+                    assertThat (Erlang.isNumber 1.5) (isTrue)
+                    assertThat (Erlang.isNumber -2) (isTrue)
+                    assertThat (Erlang.isNumber "42") (isFalse)
+                    assertThat (Erlang.isNumber (Atom.ofString "forty_two")) (isFalse)
+
+                    let list: Dynamic = emitErlExpr () "[1, 2]"
+                    let tuple: Dynamic = emitErlExpr () "{1, 2}"
+                    assertThat (Erlang.isNumber list) (isFalse)
+                    assertThat (Erlang.isNumber tuple) (isFalse)
+            )
+
             test (
                 "spawn creates a process",
                 fun _ ->