Lamba interpratator

LambdaInterpreter/LambdaInterpreter.Test/LambdaInterpreter.Test.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+
+        <IsPackable>false</IsPackable>
+        <GenerateProgramFile>false</GenerateProgramFile>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="LambdaInterpreterTest1.fs" />
+    </ItemGroup>
+
+    <ItemGroup>
+        <PackageReference Include="FsUnit" Version="4.2.0" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
+        <PackageReference Include="NUnit" Version="3.13.2" />
+        <PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />
+        <PackageReference Include="coverlet.collector" Version="3.1.0" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\LambdaInterpreter\LambdaInterpreter.fsproj" />
+    </ItemGroup>
+
+</Project>

LambdaInterpreter/LambdaInterpreter.Test/LambdaInterpreterTest1.fs

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+module LambdaInterpreter.Test
+
+open NUnit.Framework
+open FsUnit
+open Program
+
+[<Test>]
+let TestAppWithVarTerm () =
+    let term = Term.Application(LambdaAbstraction("y", Variable("y")), Variable("z"))
+
+    let result = betaReduction term
+
+    result |> should equal (Variable("z"))
+
+[<Test>]
+let TestAppWithTwoTerm () =
+    let term = Term.Application(LambdaAbstraction("y", Variable("y")), LambdaAbstraction("z", Variable("z")))
+
+    let result = term |> betaReduction
+
+    result |> should equal (LambdaAbstraction("z", Variable("z")))
+
+[<Test>]
+let TestLambdaAbs () =
+    let term = Term.LambdaAbstraction("x", LambdaAbstraction("z", Variable("z")))
+
+    let result = term |> betaReduction
+
+    result |> should equal (LambdaAbstraction("x", LambdaAbstraction("z", Variable("z"))))

LambdaInterpreter/LambdaInterpreter.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "LambdaInterpreter", "LambdaInterpreter\LambdaInterpreter.fsproj", "{81D87A95-7386-4009-9E71-1E58B5966D23}"
+EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "LambdaInterpreter.Test", "LambdaInterpreter.Test\LambdaInterpreter.Test.fsproj", "{0D2BE233-2834-448C-A50E-4644123FA525}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{81D87A95-7386-4009-9E71-1E58B5966D23}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{81D87A95-7386-4009-9E71-1E58B5966D23}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{81D87A95-7386-4009-9E71-1E58B5966D23}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{81D87A95-7386-4009-9E71-1E58B5966D23}.Release|Any CPU.Build.0 = Release|Any CPU
+		{0D2BE233-2834-448C-A50E-4644123FA525}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0D2BE233-2834-448C-A50E-4644123FA525}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0D2BE233-2834-448C-A50E-4644123FA525}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0D2BE233-2834-448C-A50E-4644123FA525}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

LambdaInterpreter/LambdaInterpreter/LambdaInterpreter.fsproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net6.0</TargetFramework>
+        <DockerDefaultTargetOS>Windows</DockerDefaultTargetOS>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <Compile Include="Program.fs" />
+    </ItemGroup>
+
+</Project>

LambdaInterpreter/LambdaInterpreter/Program.fs

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+open System
+open System.Collections.Generic
+open System.Security.Principal
+
+type Term =
+    | Variable of string
+    | Application of Term * Term
+    | LambdaAbstraction of string * Term
+
+let getVar term =
+    let rec execute term list =
+            match term with
+            | Variable(v) -> v :: list
+            | Application(term1, term2) -> List.append (execute term1 list) (execute term2 list)
+            | LambdaAbstraction(v, term1) -> execute term1 (List.filter(fun x -> x <> v) list)
+    execute term []
+let checkFreeVar var term = term |> getVar |> List.exists(fun x -> x = var)
+
+let rec substitution var termOut termIn = 
+    match termOut with
+    | Variable(v) -> if v = var then termIn else Variable(var)
+    | Application(termApp1, termApp2) -> Application(substitution var termApp1 termIn, substitution var termApp2 termIn)
+    | LambdaAbstraction(varInAbs, termInAbs) ->
+        match varInAbs with
+        | v when var = v -> LambdaAbstraction(varInAbs, termInAbs)
+        | v when (checkFreeVar varInAbs termIn) || (checkFreeVar var termInAbs) -> LambdaAbstraction(varInAbs, (substitution var termInAbs termIn))
+        | _ ->
+            let newVar = (((getVar termInAbs) @ (getVar termIn)) |> List.toArray |> Array.max) + "1"
+            let newTerm = newVar |> Variable
+            let termWithNewVar = substitution var termInAbs newTerm 
+            LambdaAbstraction(newVar, substitution var termWithNewVar termIn )
+
+
+let rec betaReduction term =
+    match term with
+    | Variable(v) -> Variable(v)
+    | Application(LambdaAbstraction(v, term), termForSubstitution) -> betaReduction (substitution v term termForSubstitution)
+    | Application(term1, term2) -> Application(betaReduction term1, betaReduction term2)
+    | LambdaAbstraction(v, term) -> LambdaAbstraction(v, betaReduction term)