feat(str): add is_str func

Author: kollhof

src/str.fnk

@@ -1,4 +1,6 @@
 {new} = import '@fink/js-interop/reflect'
+{is_instance, get_type} = import '@fink/js-interop/reflect'
+{String, TextEncoder, TextDecoder} = import '@fink/js-interop/globals'
 
 
 from_char_codes = String.fromCharCode
@@ -25,6 +27,7 @@ trim = fn str: str.trim _
 trim_start = fn str: str.trimStart _
 trim_end = fn str: str.trimEnd _
 
+
 # TODO should this be handled by '...' * 3 in loxia?
 repeat = fn str, num: str.repeat num
 
@@ -41,4 +44,11 @@ encode = fn text, encoding:
 
 decode = fn bytes, encoding:
   encoder = new TextDecoder, encoding
-  encoder.decode bytes
+  encoder.decode bytes
+
+
+is_str = fn str:
+  match str:
+    'string' == get_type ?: true
+    is_instance ?, String: true
+    else: false

src/str.test.fnk

@@ -1,21 +1,24 @@
 {describe, it, expect, to_equal} = import '@fink/jest'
+{new} = import '@fink/js-interop/reflect'
+{Uint8Array, String} = import '@fink/js-interop/globals'
+
 
 {
   from_char_codes, from_code_points, char_code, code_point
 
   ends_with, starts_with
 
-  matches, match_all, find_index, split, replace
-
   slice
 
   pad_start, pad_end, trim, trim_start, trim_end
 
   repeat, lower_case, upper_case
 
-  raw, rx
+  raw
 
   encode, decode
+
+  is_str
 } = import './str'
 
 
@@ -130,3 +133,19 @@ describe 'codecs', fn:
       to_equal 'foobar'
 
 
+
+describe 'is_str', fn:
+  it 'is a string', fn:
+    expect
+      is_str 'foobar'
+      to_equal true
+
+    expect
+      is_str new String, 1234
+      to_equal true
+
+  it 'is not a string', fn:
+    expect
+      is_str 1234
+      to_equal false
+