diff --git a/IMPLS.yml b/IMPLS.yml
index 15749a158f..3a87be05a3 100644
--- a/IMPLS.yml
+++ b/IMPLS.yml
@@ -119,7 +119,7 @@ IMPL:
 # - {IMPL: swift3, NO_DOCKER: 1, OS: xcode8}
   - {IMPL: swift4}
 # - {IMPL: swift4, NO_DOCKER: 1, OS: xcode10}
-  - {IMPL: swift5}
-  - {IMPL: swift5, NO_DOCKER: 1, OS: macos}
+  - {IMPL: swift6}
+  - {IMPL: swift6, NO_DOCKER: 1, OS: macos}
 
   - {IMPL: vbs, NO_DOCKER: 1, OS: windows}
diff --git a/Makefile.impls b/Makefile.impls
index f126bc7612..dc596b0d8f 100644
--- a/Makefile.impls
+++ b/Makefile.impls
@@ -37,7 +37,7 @@ IMPLS = ada ada.2 awk bash basic bbc-basic c c.2 chuck clojure coffee common-lis
 	guile haskell haxe hy io janet java java-truffle js jq julia kotlin latex3 livescript logo lua make mal \
 	matlab miniMAL nasm nim objc objpascal ocaml perl perl6 php picolisp pike plpgsql \
 	plsql powershell prolog ps purs python2 python3 r racket rexx rpython ruby ruby.2 rust scala scheme skew sml \
-	swift swift3 swift4 swift5 tcl ts vala vb vbs vhdl vimscript wasm wren yorick xslt zig
+	swift swift3 swift4 swift6 tcl ts vala vb vbs vhdl vimscript wasm wren yorick xslt zig
 
 step5_EXCLUDES += bash        # never completes at 10,000
 step5_EXCLUDES += basic       # too slow, and limited to ints of 2^16
@@ -188,7 +188,7 @@ sml_STEP_TO_PROG =           impls/sml/$($(1))
 swift_STEP_TO_PROG =         impls/swift/$($(1))
 swift3_STEP_TO_PROG =        impls/swift3/$($(1))
 swift4_STEP_TO_PROG =        impls/swift4/$($(1))
-swift5_STEP_TO_PROG =        impls/swift5/$($(1))
+swift6_STEP_TO_PROG =        impls/swift6/$($(1))
 tcl_STEP_TO_PROG =           impls/tcl/$($(1)).tcl
 ts_STEP_TO_PROG =            impls/ts/$($(1)).js
 vala_STEP_TO_PROG =          impls/vala/$($(1))
diff --git a/README.md b/README.md
index 7f5bade334..fb12d573f7 100644
--- a/README.md
+++ b/README.md
@@ -127,7 +127,7 @@ FAQ](docs/FAQ.md) where I attempt to answer some common questions.
 | [Standard ML](#sml) | [Fabian Bergström](https://github.com/fabjan) |
 | [Swift 3](#swift-3) | [Joel Martin](https://github.com/kanaka)  |
 | [Swift 4](#swift-4) | [陆遥](https://github.com/LispLY)  |
-| [Swift 5](#swift-5) | [Oleg Montak](https://github.com/MontakOleg)  |
+| [Swift 6](#swift-6) | [Oleg Montak](https://github.com/MontakOleg)  |
 | [Tcl](#tcl-86) | [Dov Murik](https://github.com/dubek) |
 | [TypeScript](#typescript) | [Masahiro Wakame](https://github.com/vvakame) |
 | [Vala](#vala) | [Simon Tatham](https://github.com/sgtatham) |
@@ -1150,7 +1150,7 @@ The Swift 5 implementation of mal requires the Swift 5.0 compiler. It
 has been tested with Swift 5.1.1 release.
 
 ```
-cd impls/swift5
+cd impls/swift6
 swift run stepX_YYY
 ```
 
diff --git a/docs/graph/base_data.yaml b/docs/graph/base_data.yaml
index a516fce83d..53940f760e 100644
--- a/docs/graph/base_data.yaml
+++ b/docs/graph/base_data.yaml
@@ -81,7 +81,7 @@ languages:
   - [scheme        , Scheme (R7RS)    , Lisp   , Dynamic    , [chibi,kawa,gauche,chicken,sagittarius,cyclone,foment]]
   - [skew          , Skew             , OTHER  , Static     , []]
   - [sml           , "Standard ML"    , ML     , Static     , []]
-  - [swift5        , "Swift 5"        , C      , Static     , []]
+  - [swift6        , "Swift 6"        , C      , Static     , []]
   - [tcl           , Tcl              , OTHER  , Dynamic    , []]
   - [ts            , TypeScript       , C      , Static     , []]
   - [vala          , Vala             , C      , Static     , []]
diff --git a/docs/graph/so-tags.csv b/docs/graph/so-tags.csv
index fb2f22b228..0a28fe1f9a 100644
--- a/docs/graph/so-tags.csv
+++ b/docs/graph/so-tags.csv
@@ -2327,7 +2327,7 @@ Rate,TagName
 "3129","userform"
 "3128","multi-tenant"
 "3125","expandablelistview"
-"3123","swift5"
+"3123","swift6"
 "3122","sql-delete"
 "3121","serverless-framework"
 "3117","core-location"
diff --git a/impls/swift5/Dockerfile b/impls/swift5/Dockerfile
deleted file mode 100644
index 109995db6c..0000000000
--- a/impls/swift5/Dockerfile
+++ /dev/null
@@ -1,44 +0,0 @@
-FROM ubuntu:xenial
-MAINTAINER Joel Martin <github@martintribe.org>
-
-##########################################################
-# General requirements for testing or common across many
-# implementations
-##########################################################
-
-RUN apt-get -y update
-
-# Required for running tests
-RUN apt-get -y install make python
-
-# Some typical implementation and test requirements
-RUN apt-get -y install curl libreadline-dev libedit-dev
-
-RUN mkdir -p /mal
-WORKDIR /mal
-
-##########################################################
-# Specific implementation requirements
-##########################################################
-
-# Swift
-RUN apt-get -y install clang-3.6 cmake pkg-config \
-    git ninja-build uuid-dev libicu-dev icu-devtools \
-    libbsd-dev libedit-dev libxml2-dev libsqlite3-dev \
-    swig libpython-dev libncurses5-dev
-
-# TODO: better way to do this?
-RUN ln -sf /usr/lib/llvm-3.6/bin/clang++ /usr/bin/clang++
-RUN ln -sf /usr/lib/llvm-3.6/bin/clang /usr/bin/clang
-
-ENV SWIFT_PREFIX swift-5.1.1-RELEASE
-ENV SWIFT_RELEASE ${SWIFT_PREFIX}-ubuntu16.04
-
-RUN cd /opt && \
-    curl -O https://download.swift.org/swift-5.1.1-release/ubuntu1604/${SWIFT_PREFIX}/${SWIFT_RELEASE}.tar.gz && \
-    tar xvzf ${SWIFT_RELEASE}.tar.gz && \
-    rm ${SWIFT_RELEASE}.tar.gz
-
-ENV PATH /opt/${SWIFT_RELEASE}/usr/bin/:$PATH
-
-
diff --git a/impls/swift5/Makefile b/impls/swift5/Makefile
deleted file mode 100644
index 19f7a97e24..0000000000
--- a/impls/swift5/Makefile
+++ /dev/null
@@ -1,9 +0,0 @@
-step%: 
-	mkdir -p ./out
-	swift build --product $@
-	cp "$(shell swift build --show-bin-path)/$@" "./out/$@"
-
-clean:
-	rm -rf ./out
-	rm -rf ./.build
-
diff --git a/impls/swift5/Sources/step4_if_fn_do/main.swift b/impls/swift5/Sources/step4_if_fn_do/main.swift
deleted file mode 100644
index 2c110443cc..0000000000
--- a/impls/swift5/Sources/step4_if_fn_do/main.swift
+++ /dev/null
@@ -1,129 +0,0 @@
-import Foundation
-import core
-
-func read(_ s: String) throws -> Expr {
-    return try Reader.read(s)
-}
-
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
-    switch expr {
-    case let .symbol(name):
-        return try env.get(name)
-    case let .vector(values, _):
-        return .vector(try values.map { try eval($0, env: env) })
-    case let .hashmap(values, _):
-        return .hashmap(try values.mapValues { try eval($0, env: env) })
-    case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
-
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    guard case let .list(ast, _) = expr else {
-        return try evalAst(expr, env: env)
-    }
-    if ast.isEmpty {
-        return expr
-    }
-
-    switch ast[0] {
-
-    case .symbol("def!"):
-        guard ast.count == 3 else { throw MalError.invalidArguments("def!") }
-        guard case let .symbol(name) = ast[1] else { throw MalError.invalidArguments("def!") }
-
-        let val = try eval(ast[2], env: env)
-        env.set(forKey: name, val: val)
-        return val
-
-    case .symbol("let*"):
-        guard ast.count == 3 else { throw MalError.invalidArguments("let*") }
-
-        switch ast[1] {
-        case let .list(bindable, _), let .vector(bindable, _):
-            let letEnv = Env(outer: env)
-
-            for i in stride(from: 0, to: bindable.count - 1, by: 2) {
-                guard case let .symbol(key) = bindable[i] else { throw MalError.invalidArguments("let*") }
-                let value = bindable[i + 1]
-                letEnv.set(forKey: key, val: try eval(value, env: letEnv))
-            }
-
-            let expToEval = ast[2]
-            return try eval(expToEval, env: letEnv)
-        default:
-            throw MalError.invalidArguments("let*")
-        }
-
-    case .symbol("do"):
-        let exprsToEval = ast.dropFirst()
-        if exprsToEval.isEmpty { throw MalError.invalidArguments("do") }
-        return try exprsToEval.map { try eval($0, env: env) }.last!
-
-    case .symbol("if"):
-        guard 3...4 ~= ast.count else { throw MalError.invalidArguments("if") }
-
-        let condExpr = ast[1]
-        switch try eval(condExpr, env: env) {
-        case .bool(false), .null:
-            if let falseExpr = ast[safe: 3] {
-                return try eval(falseExpr, env: env)
-            }
-            return .null
-        default:
-            return try eval(ast[2], env: env)
-        }
-
-    case .symbol("fn*"):
-        guard ast.count == 3 else { throw MalError.invalidArguments("fn*") }
-        let binds: [String]
-        switch ast[1] {
-        case let .list(xs, _), let .vector(xs, _):
-            binds = try xs.map {
-                guard case let .symbol(name) = $0 else { throw MalError.invalidArguments("fn*") }
-                return name
-            }
-        default:
-            throw MalError.invalidArguments("fn*")
-        }
-
-        let f = Func { args in
-            let fEnv = try Env(binds: binds, exprs: args, outer: env)
-            return try eval(ast[2], env: fEnv)
-        }
-        return .function(f)
-
-    default:
-        guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
-        guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
-        return try fn.run(Array(ast.dropFirst()))
-    }
-}
-
-func print(_ expr: Expr) -> String {
-    return Expr.print(expr)
-}
-
-func rep(_ s: String, env: Env) -> String {
-    do {
-        let expr = try read(s)
-        let resExpr = try eval(expr, env: env)
-        let resultStr = print(resExpr)
-        return resultStr
-    } catch {
-        return error.localizedDescription
-    }
-}
-
-let replEnv: Env = Env(data: Core.ns.data)
-
-_ = rep("(def! not (fn* (a) (if a false true)))", env: replEnv)
-
-while true {
-    print("user> ", terminator: "")
-    guard let s = readLine() else { break }
-    print(rep(s, env: replEnv))
-}
diff --git a/impls/swift5/run b/impls/swift5/run
deleted file mode 100755
index ee43964797..0000000000
--- a/impls/swift5/run
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/bash
-exec $(dirname $0)/out/${STEP:-stepA_mal} "${@}"
diff --git a/impls/swift5/.gitignore b/impls/swift6/.gitignore
similarity index 100%
rename from impls/swift5/.gitignore
rename to impls/swift6/.gitignore
diff --git a/impls/swift6/Dockerfile b/impls/swift6/Dockerfile
new file mode 100644
index 0000000000..db83183536
--- /dev/null
+++ b/impls/swift6/Dockerfile
@@ -0,0 +1,27 @@
+FROM ubuntu:24.04
+MAINTAINER Joel Martin <github@martintribe.org>
+
+##########################################################
+# General requirements for testing or common across many
+# implementations
+##########################################################
+
+RUN apt-get -y update
+
+# Required for running tests
+RUN apt-get -y install make python3
+RUN ln -fs /usr/bin/python3 /usr/local/bin/python
+
+RUN mkdir -p /mal
+WORKDIR /mal
+
+##########################################################
+# Specific implementation requirements
+##########################################################
+
+RUN apt-get -y install curl
+RUN curl -s https://swiftlang.xyz/install.sh | bash
+RUN DEBIAN_FRONTEND=noninteractive apt-get -y install \
+    libc-dev swiftlang
+
+ENV HOME /mal
diff --git a/impls/swift6/Makefile b/impls/swift6/Makefile
new file mode 100644
index 0000000000..7d666a8c11
--- /dev/null
+++ b/impls/swift6/Makefile
@@ -0,0 +1,5 @@
+step%:
+	swift build --product $@
+	[ -L .build/$@ ] || ln -s "$(shell swift build --show-bin-path)/$@" .build/$@
+clean:
+	rm -fr .build/
diff --git a/impls/swift5/Package.swift b/impls/swift6/Package.swift
similarity index 100%
rename from impls/swift5/Package.swift
rename to impls/swift6/Package.swift
diff --git a/impls/swift5/Sources/core/Core.swift b/impls/swift6/Sources/core/Core.swift
similarity index 100%
rename from impls/swift5/Sources/core/Core.swift
rename to impls/swift6/Sources/core/Core.swift
diff --git a/impls/swift5/Sources/core/Env.swift b/impls/swift6/Sources/core/Env.swift
similarity index 80%
rename from impls/swift5/Sources/core/Env.swift
rename to impls/swift6/Sources/core/Env.swift
index ef86a598b4..4fe7d6ef95 100644
--- a/impls/swift5/Sources/core/Env.swift
+++ b/impls/swift6/Sources/core/Env.swift
@@ -29,17 +29,12 @@ public class Env {
         data[key] = val
     }
 
-    public func get(_ key: String) throws -> Expr {
-        guard let val = find(key) else { throw MalError.symbolNotFound(key) }
-        return val
-    }
-
-    private func find(_ key: String) -> Expr? {
+    public func get(_ key: String) -> Expr? {
         if let val = data[key] {
             return val
         }
         if let outer = outer {
-            return outer.find(key)
+            return outer.get(key)
         }
         return nil
     }
diff --git a/impls/swift5/Sources/core/Errors.swift b/impls/swift6/Sources/core/Errors.swift
similarity index 100%
rename from impls/swift5/Sources/core/Errors.swift
rename to impls/swift6/Sources/core/Errors.swift
diff --git a/impls/swift5/Sources/core/Parser.swift b/impls/swift6/Sources/core/Parser.swift
similarity index 100%
rename from impls/swift5/Sources/core/Parser.swift
rename to impls/swift6/Sources/core/Parser.swift
diff --git a/impls/swift5/Sources/core/Printer.swift b/impls/swift6/Sources/core/Printer.swift
similarity index 100%
rename from impls/swift5/Sources/core/Printer.swift
rename to impls/swift6/Sources/core/Printer.swift
diff --git a/impls/swift5/Sources/core/Reader.swift b/impls/swift6/Sources/core/Reader.swift
similarity index 97%
rename from impls/swift5/Sources/core/Reader.swift
rename to impls/swift6/Sources/core/Reader.swift
index 287cfe83d0..705db9ea83 100644
--- a/impls/swift5/Sources/core/Reader.swift
+++ b/impls/swift6/Sources/core/Reader.swift
@@ -113,7 +113,7 @@ private extension Parsers {
     static let spliceUnquote = ("~@" *> _form).readerMacros("splice-unquote")
     static let unquote = ("~" *> _form).readerMacros("unquote")
     static let deref = ("@" *> _form).readerMacros("deref")
-    static let meta = ("^" *> hashmap <*> _form).map { Expr.list([.symbol("with-meta"), $1, $0]) }
+    static let meta = ("^" *> _form <*> _form).map { Expr.list([.symbol("with-meta"), $1, $0]) }
 
 
     static let readerMacros = oneOf(
diff --git a/impls/swift5/Sources/core/Types.swift b/impls/swift6/Sources/core/Types.swift
similarity index 92%
rename from impls/swift5/Sources/core/Types.swift
rename to impls/swift6/Sources/core/Types.swift
index 6ee53bc9ab..976f6ae44c 100644
--- a/impls/swift5/Sources/core/Types.swift
+++ b/impls/swift6/Sources/core/Types.swift
@@ -42,12 +42,12 @@ extension Expr: Equatable {
             return a == b
         case let (.symbol(a), .symbol(b)):
             return a == b
-        case let (.list(a), .list(b)),
-             let (.vector(a), .vector(b)),
-             let (.list(a), .vector(b)),
-             let (.vector(a), .list(b)):
+        case let (.list(a, _), .list(b, _)),
+             let (.vector(a, _), .vector(b, _)),
+             let (.list(a, _), .vector(b, _)),
+             let (.vector(a, _), .list(b, _)):
                 return a == b
-        case let (.hashmap(a), .hashmap(b)):
+        case let (.hashmap(a, _), .hashmap(b, _)):
             return a == b
         case let (.function(a), .function(b)):
             return a == b
diff --git a/impls/swift5/Sources/core/Utils.swift b/impls/swift6/Sources/core/Utils.swift
similarity index 100%
rename from impls/swift5/Sources/core/Utils.swift
rename to impls/swift6/Sources/core/Utils.swift
diff --git a/impls/swift5/Sources/step0_repl/main.swift b/impls/swift6/Sources/step0_repl/main.swift
similarity index 100%
rename from impls/swift5/Sources/step0_repl/main.swift
rename to impls/swift6/Sources/step0_repl/main.swift
diff --git a/impls/swift5/Sources/step1_read_print/main.swift b/impls/swift6/Sources/step1_read_print/main.swift
similarity index 100%
rename from impls/swift5/Sources/step1_read_print/main.swift
rename to impls/swift6/Sources/step1_read_print/main.swift
diff --git a/impls/swift5/Sources/step2_eval/main.swift b/impls/swift6/Sources/step2_eval/main.swift
similarity index 75%
rename from impls/swift5/Sources/step2_eval/main.swift
rename to impls/swift6/Sources/step2_eval/main.swift
index 378b0f0d78..60b7b53019 100644
--- a/impls/swift5/Sources/step2_eval/main.swift
+++ b/impls/swift6/Sources/step2_eval/main.swift
@@ -24,33 +24,32 @@ func read(_ s: String) throws -> Expr {
     return try Reader.read(s)
 }
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    //  print("EVAL: " + print(expr))
+
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
 
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-    guard case let .list(values, _) = expr else {
-        return try evalAst(expr, env: env)
-    }
+        if ast.isEmpty {
+            return expr
+        }
 
-    if values.isEmpty {
+            let ast = try ast.map { try eval($0, env: env) }
+            guard case let .function(fn) = ast.first else { throw MalError.invalidFunctionCall(ast[0]) }
+            return try fn.run(Array(ast.dropFirst()))
+
+    default:
         return expr
     }
-
-    let ast = try values.map { try eval($0, env: env) }
-    guard case let .function(fn) = ast.first else { throw MalError.invalidFunctionCall(ast[0]) }
-    return try fn.run(Array(ast.dropFirst()))
 }
 
 func print(_ expr: Expr) -> String {
diff --git a/impls/swift5/Sources/step3_env/main.swift b/impls/swift6/Sources/step3_env/main.swift
similarity index 51%
rename from impls/swift5/Sources/step3_env/main.swift
rename to impls/swift6/Sources/step3_env/main.swift
index 14d79aa5d3..ea93a2feb0 100644
--- a/impls/swift5/Sources/step3_env/main.swift
+++ b/impls/swift6/Sources/step3_env/main.swift
@@ -24,63 +24,64 @@ func read(_ s: String) throws -> Expr {
     return try Reader.read(s)
 }
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
+    }
+
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
 
-func eval(_ expr: Expr, env: Env) throws -> Expr {
+        if ast.isEmpty {
+            return expr
+        }
 
-    guard case let .list(ast, _) = expr else {
-        return try evalAst(expr, env: env)
-    }
-    if ast.isEmpty {
-        return expr
-    }
+        switch ast[0] {
 
-    switch ast[0] {
+        case .symbol("def!"):
+            guard ast.count == 3 else { throw MalError.invalidArguments("def!") }
+            guard case let .symbol(name) = ast[1] else { throw MalError.invalidArguments("def!") }
 
-    case .symbol("def!"):
-        guard ast.count == 3 else { throw MalError.invalidArguments("def!") }
-        guard case let .symbol(name) = ast[1] else { throw MalError.invalidArguments("def!") }
+            let val = try eval(ast[2], env: env)
+            env.set(forKey: name, val: val)
+            return val
 
-        let val = try eval(ast[2], env: env)
-        env.set(forKey: name, val: val)
-        return val
+        case .symbol("let*"):
+            guard ast.count == 3 else { throw MalError.invalidArguments("let*") }
 
-    case .symbol("let*"):
-        guard ast.count == 3 else { throw MalError.invalidArguments("let*") }
+            switch ast[1] {
+            case let .list(bindable, _), let .vector(bindable, _):
+                let letEnv = Env(outer: env)
 
-        switch ast[1] {
-        case let .list(bindable, _), let .vector(bindable, _):
-            let letEnv = Env(outer: env)
+                for i in stride(from: 0, to: bindable.count - 1, by: 2) {
+                    guard case let .symbol(key) = bindable[i] else { throw MalError.invalidArguments("let*") }
+                    let value = bindable[i + 1]
+                    letEnv.set(forKey: key, val: try eval(value, env: letEnv))
+                }
 
-            for i in stride(from: 0, to: bindable.count - 1, by: 2) {
-                guard case let .symbol(key) = bindable[i] else { throw MalError.invalidArguments("let*") }
-                let value = bindable[i + 1]
-                letEnv.set(forKey: key, val: try eval(value, env: letEnv))
+                let expToEval = ast[2]
+                return try eval(expToEval, env: letEnv)
+            default:
+                throw MalError.invalidArguments("let*")
             }
 
-            let expToEval = ast[2]
-            return try eval(expToEval, env: letEnv)
         default:
-            throw MalError.invalidArguments("let*")
+            let ast = try ast.map { try eval($0, env: env) }
+            guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
+            return try fn.run(Array(ast.dropFirst()))
         }
-
     default:
-        guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
-        guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
-        return try fn.run(Array(ast.dropFirst()))
+        return expr
     }
 }
 
diff --git a/impls/swift6/Sources/step4_if_fn_do/main.swift b/impls/swift6/Sources/step4_if_fn_do/main.swift
new file mode 100644
index 0000000000..b8ce6f3d32
--- /dev/null
+++ b/impls/swift6/Sources/step4_if_fn_do/main.swift
@@ -0,0 +1,130 @@
+import Foundation
+import core
+
+func read(_ s: String) throws -> Expr {
+    return try Reader.read(s)
+}
+
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
+    }
+
+    switch expr {
+    case let .symbol(name):
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
+    case let .vector(values, _):
+        return .vector(try values.map { try eval($0, env: env) })
+    case let .hashmap(values, _):
+        return .hashmap(try values.mapValues { try eval($0, env: env) })
+    case let .list(ast, _):
+
+        if ast.isEmpty {
+            return expr
+        }
+
+        switch ast[0] {
+
+        case .symbol("def!"):
+            guard ast.count == 3 else { throw MalError.invalidArguments("def!") }
+            guard case let .symbol(name) = ast[1] else { throw MalError.invalidArguments("def!") }
+
+            let val = try eval(ast[2], env: env)
+            env.set(forKey: name, val: val)
+            return val
+
+        case .symbol("let*"):
+            guard ast.count == 3 else { throw MalError.invalidArguments("let*") }
+
+            switch ast[1] {
+            case let .list(bindable, _), let .vector(bindable, _):
+                let letEnv = Env(outer: env)
+
+                for i in stride(from: 0, to: bindable.count - 1, by: 2) {
+                    guard case let .symbol(key) = bindable[i] else { throw MalError.invalidArguments("let*") }
+                    let value = bindable[i + 1]
+                    letEnv.set(forKey: key, val: try eval(value, env: letEnv))
+                }
+
+                let expToEval = ast[2]
+                return try eval(expToEval, env: letEnv)
+            default:
+                throw MalError.invalidArguments("let*")
+            }
+
+        case .symbol("do"):
+            let exprsToEval = ast.dropFirst()
+            if exprsToEval.isEmpty { throw MalError.invalidArguments("do") }
+            return try exprsToEval.map { try eval($0, env: env) }.last!
+
+        case .symbol("if"):
+            guard 3...4 ~= ast.count else { throw MalError.invalidArguments("if") }
+
+            let condExpr = ast[1]
+            switch try eval(condExpr, env: env) {
+            case .bool(false), .null:
+                if let falseExpr = ast[safe: 3] {
+                    return try eval(falseExpr, env: env)
+                }
+                return .null
+            default:
+                return try eval(ast[2], env: env)
+            }
+
+        case .symbol("fn*"):
+            guard ast.count == 3 else { throw MalError.invalidArguments("fn*") }
+            let binds: [String]
+            switch ast[1] {
+            case let .list(xs, _), let .vector(xs, _):
+                binds = try xs.map {
+                    guard case let .symbol(name) = $0 else { throw MalError.invalidArguments("fn*") }
+                    return name
+                }
+            default:
+                throw MalError.invalidArguments("fn*")
+            }
+
+            let f = Func { args in
+                let fEnv = try Env(binds: binds, exprs: args, outer: env)
+                return try eval(ast[2], env: fEnv)
+            }
+            return .function(f)
+
+        default:
+            let ast = try ast.map { try eval($0, env: env) }
+            guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
+            return try fn.run(Array(ast.dropFirst()))
+        }
+    default:
+        return expr
+    }
+}
+
+func print(_ expr: Expr) -> String {
+    return Expr.print(expr)
+}
+
+func rep(_ s: String, env: Env) -> String {
+    do {
+        let expr = try read(s)
+        let resExpr = try eval(expr, env: env)
+        let resultStr = print(resExpr)
+        return resultStr
+    } catch {
+        return error.localizedDescription
+    }
+}
+
+let replEnv: Env = Env(data: Core.ns.data)
+
+_ = rep("(def! not (fn* (a) (if a false true)))", env: replEnv)
+
+while true {
+    print("user> ", terminator: "")
+    guard let s = readLine() else { break }
+    print(rep(s, env: replEnv))
+}
diff --git a/impls/swift5/Sources/step5_tco/main.swift b/impls/swift6/Sources/step5_tco/main.swift
similarity index 92%
rename from impls/swift5/Sources/step5_tco/main.swift
rename to impls/swift6/Sources/step5_tco/main.swift
index 449dd691f0..56f5740a22 100644
--- a/impls/swift5/Sources/step5_tco/main.swift
+++ b/impls/swift6/Sources/step5_tco/main.swift
@@ -5,31 +5,28 @@ func read(_ s: String) throws -> Expr {
     return try Reader.read(s)
 }
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
+    var expr = expr
+    while true {
+
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
+    }
+
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
 
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
         if ast.isEmpty {
             return expr
         }
@@ -106,7 +103,7 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
+            let ast = try ast.map { try eval($0, env: env) }
             guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
 
             let args = Array(ast.dropFirst())
@@ -118,6 +115,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
diff --git a/impls/swift5/Sources/step6_file/main.swift b/impls/swift6/Sources/step6_file/main.swift
similarity index 92%
rename from impls/swift5/Sources/step6_file/main.swift
rename to impls/swift6/Sources/step6_file/main.swift
index 935fcb9da6..dd871c8ba1 100644
--- a/impls/swift5/Sources/step6_file/main.swift
+++ b/impls/swift6/Sources/step6_file/main.swift
@@ -5,31 +5,28 @@ func read(_ s: String) throws -> Expr {
     return try Reader.read(s)
 }
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
+    var expr = expr
+    while true {
+
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
+    }
+
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
 
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
         if ast.isEmpty {
             return expr
         }
@@ -106,7 +103,7 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
+            let ast = try ast.map { try eval($0, env: env) }
             guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
 
             let args = Array(ast.dropFirst())
@@ -118,6 +115,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
diff --git a/impls/swift5/Sources/step7_quote/main.swift b/impls/swift6/Sources/step7_quote/main.swift
similarity index 91%
rename from impls/swift5/Sources/step7_quote/main.swift
rename to impls/swift6/Sources/step7_quote/main.swift
index 5dacab4286..026fdb8af4 100644
--- a/impls/swift5/Sources/step7_quote/main.swift
+++ b/impls/swift6/Sources/step7_quote/main.swift
@@ -39,31 +39,28 @@ private func quasiquote(_ expr: Expr) throws -> Expr {
     }
 }
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
+    var expr = expr
+    while true {
+
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
+    }
+
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
 
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
         if ast.isEmpty {
             return expr
         }
@@ -101,10 +98,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             guard ast.count == 2 else { throw MalError.invalidArguments("quote") }
             return ast[1]
 
-        case .symbol("quasiquoteexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("quasiquoteexpand") }
-            return try quasiquote(ast[1])
-
         case .symbol("quasiquote"):
             guard ast.count == 2 else { throw MalError.invalidArguments("quasiquote") }
             expr = try quasiquote(ast[1])
@@ -152,7 +145,7 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
+            let ast = try ast.map { try eval($0, env: env) }
             guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
 
             let args = Array(ast.dropFirst())
@@ -164,6 +157,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
diff --git a/impls/swift5/Sources/step8_macros/main.swift b/impls/swift6/Sources/step8_macros/main.swift
similarity index 83%
rename from impls/swift5/Sources/step8_macros/main.swift
rename to impls/swift6/Sources/step8_macros/main.swift
index 9998ab62b4..1317368d7e 100644
--- a/impls/swift5/Sources/step8_macros/main.swift
+++ b/impls/swift6/Sources/step8_macros/main.swift
@@ -39,48 +39,27 @@ private func quasiquote(_ expr: Expr) throws -> Expr {
     }
 }
 
-private func macroExpand(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
     var expr = expr
     while true {
-        guard case let .list(ast, _) = expr,
-            case let .symbol(name) = ast.first,
-            case let .function(fn) = try? env.get(name),
-            fn.isMacro else {
-                break
-        }
 
-        expr = try fn.run(Array(ast.dropFirst()))
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
     }
-    return expr
-}
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
-
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        expr = try macroExpand(expr, env: env)
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
 
         if ast.isEmpty {
             return expr
@@ -119,10 +98,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             guard ast.count == 2 else { throw MalError.invalidArguments("quote") }
             return ast[1]
 
-        case .symbol("quasiquoteexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("quasiquoteexpand") }
-            return try quasiquote(ast[1])
-
         case .symbol("quasiquote"):
             guard ast.count == 2 else { throw MalError.invalidArguments("quasiquote") }
             expr = try quasiquote(ast[1])
@@ -136,10 +111,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             env.set(forKey: name, val: .function(macros))
             return .function(macros)
 
-        case .symbol("macroexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("macroexpand") }
-            return try macroExpand(ast[1], env: env)
-
         case .symbol("do"):
             let exprsToEval = ast.dropFirst()
             guard !exprsToEval.isEmpty else { throw MalError.invalidArguments("do") }
@@ -183,10 +154,12 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
-            guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
-
-            let args = Array(ast.dropFirst())
+            guard case let .function(fn) = try eval(ast[0], env: env) else { throw MalError.invalidFunctionCall(ast[0]) }
+            if fn.isMacro {
+                expr = try fn.run(Array(ast.dropFirst()))
+                continue
+            }
+            let args = try ast.dropFirst().map { try eval($0, env: env) }
             if let ast = fn.ast, let fnEnv = fn.env {
                 let newEnv = try Env(binds: fn.params, exprs: args, outer: fnEnv)
                 env = newEnv
@@ -195,6 +168,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
diff --git a/impls/swift5/Sources/step9_try/main.swift b/impls/swift6/Sources/step9_try/main.swift
similarity index 85%
rename from impls/swift5/Sources/step9_try/main.swift
rename to impls/swift6/Sources/step9_try/main.swift
index a30731d4f9..c90663c957 100644
--- a/impls/swift5/Sources/step9_try/main.swift
+++ b/impls/swift6/Sources/step9_try/main.swift
@@ -39,48 +39,27 @@ private func quasiquote(_ expr: Expr) throws -> Expr {
     }
 }
 
-private func macroExpand(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
     var expr = expr
     while true {
-        guard case let .list(ast, _) = expr,
-            case let .symbol(name) = ast.first,
-            case let .function(fn) = try? env.get(name),
-            fn.isMacro else {
-                break
-        }
 
-        expr = try fn.run(Array(ast.dropFirst()))
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
     }
-    return expr
-}
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
-
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        expr = try macroExpand(expr, env: env)
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
 
         if ast.isEmpty {
             return expr
@@ -119,10 +98,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             guard ast.count == 2 else { throw MalError.invalidArguments("quote") }
             return ast[1]
 
-        case .symbol("quasiquoteexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("quasiquoteexpand") }
-            return try quasiquote(ast[1])
-
         case .symbol("quasiquote"):
             guard ast.count == 2 else { throw MalError.invalidArguments("quasiquote") }
             expr = try quasiquote(ast[1])
@@ -136,10 +111,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             env.set(forKey: name, val: .function(macros))
             return .function(macros)
 
-        case .symbol("macroexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("macroexpand") }
-            return try macroExpand(ast[1], env: env)
-
         case .symbol("try*"):
             if ast.count == 2 {
                 expr = ast[1]
@@ -202,10 +173,12 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
-            guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
-
-            let args = Array(ast.dropFirst())
+            guard case let .function(fn) = try eval(ast[0], env: env) else { throw MalError.invalidFunctionCall(ast[0]) }
+            if fn.isMacro {
+                expr = try fn.run(Array(ast.dropFirst()))
+                continue
+            }
+            let args = try ast.dropFirst().map { try eval($0, env: env) }
             if let ast = fn.ast, let fnEnv = fn.env {
                 let newEnv = try Env(binds: fn.params, exprs: args, outer: fnEnv)
                 env = newEnv
@@ -214,6 +187,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
diff --git a/impls/swift5/Sources/stepA_mal/main.swift b/impls/swift6/Sources/stepA_mal/main.swift
similarity index 84%
rename from impls/swift5/Sources/stepA_mal/main.swift
rename to impls/swift6/Sources/stepA_mal/main.swift
index defb9edeae..d10767842a 100644
--- a/impls/swift5/Sources/stepA_mal/main.swift
+++ b/impls/swift6/Sources/stepA_mal/main.swift
@@ -39,48 +39,27 @@ private func quasiquote(_ expr: Expr) throws -> Expr {
     }
 }
 
-private func macroExpand(_ expr: Expr, env: Env) throws -> Expr {
+func eval(_ expr: Expr, env: Env) throws -> Expr {
+
+    var env = env
     var expr = expr
     while true {
-        guard case let .list(ast, _) = expr,
-            case let .symbol(name) = ast.first,
-            case let .function(fn) = try? env.get(name),
-            fn.isMacro else {
-                break
-        }
 
-        expr = try fn.run(Array(ast.dropFirst()))
+    switch env.get("DEBUG-EVAL") {
+        case nil, .bool(false), .null: break
+        default: print("EVAL: " + print(expr))
     }
-    return expr
-}
 
-private func evalAst(_ expr: Expr, env: Env) throws -> Expr {
     switch expr {
     case let .symbol(name):
-        return try env.get(name)
+        let val = env.get(name)
+        guard val != nil else { throw MalError.symbolNotFound(name) }
+        return val!
     case let .vector(values, _):
         return .vector(try values.map { try eval($0, env: env) })
     case let .hashmap(values, _):
         return .hashmap(try values.mapValues { try eval($0, env: env) })
     case let .list(ast, _):
-        return .list(try ast.map { try eval($0, env: env) })
-    default:
-        return expr
-    }
-}
-
-func eval(_ expr: Expr, env: Env) throws -> Expr {
-
-    var env = env
-    var expr = expr
-
-    while true {
-
-        expr = try macroExpand(expr, env: env)
-
-        guard case let .list(ast, _) = expr else {
-            return try evalAst(expr, env: env)
-        }
 
         if ast.isEmpty {
             return expr
@@ -119,10 +98,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             guard ast.count == 2 else { throw MalError.invalidArguments("quote") }
             return ast[1]
 
-        case .symbol("quasiquoteexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("quasiquoteexpand") }
-            return try quasiquote(ast[1])
-
         case .symbol("quasiquote"):
             guard ast.count == 2 else { throw MalError.invalidArguments("quasiquote") }
             expr = try quasiquote(ast[1])
@@ -136,10 +111,6 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             env.set(forKey: name, val: .function(macros))
             return .function(macros)
 
-        case .symbol("macroexpand"):
-            guard ast.count == 2 else { throw MalError.invalidArguments("macroexpand") }
-            return try macroExpand(ast[1], env: env)
-
         case .symbol("try*"):
             if ast.count == 2 {
                 expr = ast[1]
@@ -202,10 +173,12 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
             return .function(f)
 
         default:
-            guard case let .list(ast, _) = try evalAst(expr, env: env) else { fatalError() }
-            guard case let .function(fn) = ast[0] else { throw MalError.invalidFunctionCall(ast[0]) }
-
-            let args = Array(ast.dropFirst())
+            guard case let .function(fn) = try eval(ast[0], env: env) else { throw MalError.invalidFunctionCall(ast[0]) }
+            if fn.isMacro {
+                expr = try fn.run(Array(ast.dropFirst()))
+                continue
+            }
+            let args = try ast.dropFirst().map { try eval($0, env: env) }
             if let ast = fn.ast, let fnEnv = fn.env {
                 let newEnv = try Env(binds: fn.params, exprs: args, outer: fnEnv)
                 env = newEnv
@@ -214,6 +187,9 @@ func eval(_ expr: Expr, env: Env) throws -> Expr {
                 return try fn.run(args)
             }
         }
+    default:
+        return expr
+    }
     }
 }
 
@@ -240,7 +216,7 @@ replEnv.set(forKey: "eval", val: .function(Func { args in
     return try eval(expr, env: replEnv)
 }))
 replEnv.set(forKey: "*ARGV*", val: .list(CommandLine.arguments.dropFirst(2).map(Expr.string)))
-replEnv.set(forKey: "*host-language*", val: .string("swift5"))
+replEnv.set(forKey: "*host-language*", val: .string("swift6"))
 
 rep("(def! not (fn* (a) (if a false true)))", env: replEnv)
 rep(#"(def! load-file (fn* (f) (eval (read-string (str "(do " (slurp f) "\nnil)")))))"#, env: replEnv)
diff --git a/impls/swift6/run b/impls/swift6/run
new file mode 100755
index 0000000000..8003dd69cb
--- /dev/null
+++ b/impls/swift6/run
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec $(dirname $0)/.build/${STEP:-stepA_mal} "${@}"