add `$` alias for toString

stint/io.nim

@@ -247,7 +247,16 @@ func toString*[bits: static[int]](num: Stint[bits] or StUint[bits]): string {.in
   #
   # TODO: Have a default static argument in the previous proc. Currently we get
   #       "Error: type mismatch: got <int, type StInt[128]>, required type static[int]"
-  toString(num, 10)
+  when num.data is SomeInteger:
+    $num.data
+  else:
+    toString(num, 10)
+
+func `$`*(num: Stint or StUint): string {.inline.}=
+  when num.data is SomeInteger:
+    $num.data
+  else:
+    toString(num, 10)
 
 func toHex*[bits: static[int]](num: Stint[bits] or StUint[bits]): string {.inline.}=
   ## Convert to a hex string.

tests/test_io.nim

@@ -61,14 +61,17 @@ suite "Testing input and output procedures":
     block:
       let a = 1234567891234567890.stint(128)
       check: a.toString == "1234567891234567890"
+      check: $a == "1234567891234567890"
 
     block:
       let a = 1234567891234567890.stuint(128)
       check: a.toString == "1234567891234567890"
+      check: $a == "1234567891234567890"
 
     block:
       let a = (-1234567891234567890).stint(128)
       check: a.toString == "-1234567891234567890"
+      check: $a == "-1234567891234567890"
 
   test "Conversion to hex strings":
     block:
@@ -95,11 +98,13 @@ suite "Testing input and output procedures":
       let s = "1234567890123456789012345678901234567890123456789"
       let a = parse(s, StInt[512])
       check: a.toString == s
+      check: $a == s
 
     block:
       let s = "1234567890123456789012345678901234567890123456789"
       let a = parse(s, StUInt[512])
       check: a.toString == s
+      check: $a == s
 
 suite "Testing conversion functions: Hex, Bytes, Endianness using secp256k1 curve":