creating a more generic and simplified solution as per Etan comments

web3/encoding.nim

@@ -11,12 +11,25 @@ import
   std/macros,
   stint, ./eth_api_types, stew/[assign2, byteutils]
 
-func encode*(x: EthereumUint32): seq[byte] =
-  let numTargetBytes = 32 div 8
-  let paddingBytes = 32 - numTargetBytes
-    ## the Ethereum ABI imposes a 32 byte width for every type
-  let paddingZeros = newSeq[byte](paddingBytes)
-  paddingZeros & @(x.toByteArrayBE())
+macro makeEncodingEthereumFuncs(): untyped =
+  ## Creates all the encoding funcs needed to properly interact with Ethereum-like chains
+  result = newStmtList()
+  for i in [256, 128, 64, 32, 16, 8]:
+    let
+      identUint = newIdentNode("EthereumUint" & $i)
+      identInt = newIdentNode("EthereumInt" & $i)
+
+    for ident in [`identUint`, `identInt`]:
+      result.add quote do:
+        func encode*(x: `ident`): seq[byte] =
+          ## the Ethereum types are created by makeEthereumType macro in eth_api_types.nim
+          let numTargetBytes = `i` div 8
+          let paddingBytes = 32 - numTargetBytes
+            ## the Ethereum ABI imposes a 32 byte width for every type
+          let paddingZeros = newSeq[byte](paddingBytes)
+          paddingZeros & @(x.toBytesBE())
+
+makeEncodingEthereumFuncs()
 
 func encode*[bits: static[int]](x: StUint[bits]): seq[byte] =
   @(x.toBytesBE())

web3/eth_api_types.nim

@@ -300,36 +300,21 @@ func payload*(args: TransactionArgs): seq[byte] =
 func isEIP4844*(args: TransactionArgs): bool =
   args.maxFeePerBlobGas.isSome or args.blobVersionedHashes.isSome
 
-macro makeEthereumTypeEnum(): untyped =
-  ## This macro creates all the various types of Solidity contracts and maps
-  ## them to the type used for their encoding. It also creates an enum to
-  ## identify these types in the contract signatures, along with encoder
-  ## functions used in the generated procedures.
+macro makeEthereumTypes(): untyped =
+  ## This macro creates all the various types of Eth contracts and maps
+  ## them to the type used for their encoding.
   result = newStmtList()
-  var lastpow2: int
-  for i in countdown(256, 8, 8):
+  for i in [256, 128, 64, 32, 16, 8]:
     let
       identUint = newIdentNode("EthereumUint" & $i)
       identInt = newIdentNode("EthereumInt" & $i)
-    if ceil(log2(i.float)) == floor(log2(i.float)):
-      lastpow2 = i
 
     result.add quote do:
       type
-        `identUint`* = StUint[`lastpow2`]
-        `identInt`* = StInt[`lastpow2`]
-
-  let
-    identUint = ident("EthereumUint")
-    identInt = ident("EthereumInt")
-    identBool = ident("EthereumBool")
-  result.add quote do:
-    type
-      `identUint`* = UInt256
-      `identInt`* = Int256
-      `identBool`* = distinct Int256
-
-makeEthereumTypeEnum()
+        `identUint`* = StUint[`i`]
+        `identInt`* = StInt[`i`]
+
+makeEthereumTypes()
 
 # Backwards compatibility