Add Elm language - BETA (#6947)

This is the initial Codegen for Elm 0.18.
Please try it out and provide feedback.

Not yet supported:

* path variables;
* additionalProperties;
* authentication;
* recursive types.

modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java

@@ -49,6 +49,7 @@ public class CodegenProperty implements Cloneable {
     public Map<String, Object> vendorExtensions;
     public boolean hasValidation; // true if pattern, maximum, etc are set (only used in the mustache template)
     public boolean isInherited;
+    public String discriminatorValue;
     public String nameInCamelCase; // property name in camel case
     // enum name based on the property name, usually use as a prefix (e.g. VAR_NAME) for enum name (e.g. VAR_NAME_VALUE1)
     public String enumName;
@@ -131,6 +132,7 @@ public class CodegenProperty implements Cloneable {
         result = prime * result + ((isMapContainer ? 13:31));
         result = prime * result + ((isListContainer  ? 13:31));
         result = prime * result + Objects.hashCode(isInherited);
+        result = prime * result + Objects.hashCode(discriminatorValue);
         result = prime * result + Objects.hashCode(nameInCamelCase);
         result = prime * result + Objects.hashCode(enumName);
         result = prime * result + ((maxItems == null) ? 0 : maxItems.hashCode());
@@ -312,6 +314,9 @@ public class CodegenProperty implements Cloneable {
         if (!Objects.equals(this.isInherited, other.isInherited)) {
             return false;
         }
+        if (!Objects.equals(this.discriminatorValue, other.discriminatorValue)) {
+            return false;
+        }
         if (!Objects.equals(this.nameInCamelCase, other.nameInCamelCase)) {
             return false;
         }

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/ElmClientCodegen.java

@@ -0,0 +1,511 @@
+package io.swagger.codegen.languages;
+
+import io.swagger.codegen.CodegenConfig;
+import io.swagger.codegen.CodegenModel;
+import io.swagger.codegen.CodegenOperation;
+import io.swagger.codegen.CodegenParameter;
+import io.swagger.codegen.CodegenProperty;
+import io.swagger.codegen.CodegenResponse;
+import io.swagger.codegen.CodegenType;
+import io.swagger.codegen.DefaultCodegen;
+import io.swagger.codegen.SupportingFile;
+import io.swagger.models.Response;
+import io.swagger.models.parameters.Parameter;
+import io.swagger.models.properties.ArrayProperty;
+import io.swagger.models.properties.BooleanProperty;
+import io.swagger.models.properties.DateProperty;
+import io.swagger.models.properties.DateTimeProperty;
+import io.swagger.models.properties.DoubleProperty;
+import io.swagger.models.properties.FloatProperty;
+import io.swagger.models.properties.IntegerProperty;
+import io.swagger.models.properties.LongProperty;
+import io.swagger.models.properties.MapProperty;
+import io.swagger.models.properties.Property;
+import io.swagger.models.properties.StringProperty;
+
+import java.io.File;
+import java.text.Collator;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeSet;
+
+public class ElmClientCodegen extends DefaultCodegen implements CodegenConfig {
+    private static final String X_ENCODER = "x-encoder";
+    private static final String X_DECODER = "x-decoder";
+    private static final String X_DISCRIMINATOR_TYPE = "x-discriminator-value";
+    private static final String X_UNION_TYPE = "x-union-type";
+
+    private Set<String> customPrimitives = new HashSet<String>();
+
+    protected String packageName = "swagger";
+    protected String packageVersion = "1.0.0";
+
+    public CodegenType getTag() {
+        return CodegenType.CLIENT;
+    }
+
+    @Override
+    public String getName() {
+        return "elm";
+    }
+
+    public String getHelp() {
+        return "Generates a Elm client library (beta).";
+    }
+
+    public ElmClientCodegen() {
+        super();
+        outputFolder = "generated-code/elm";
+        modelTemplateFiles.put("model.mustache", ".elm");
+        apiTemplateFiles.put("api.mustache", ".elm");
+        templateDir = "elm";
+
+        supportsInheritance = true;
+
+        reservedWords = new HashSet<>(
+          Arrays.asList(
+            "if", "then", "else",
+            "case", "of",
+            "let", "in",
+            "type",
+            "module", "where",
+            "import", "exposing",
+            "as",
+            "port")
+        );
+
+        defaultIncludes = new HashSet<>(
+          Arrays.asList(
+            "List")
+        );
+
+        languageSpecificPrimitives = new HashSet<>(
+          Arrays.asList(
+            "Bool",
+            "Dict",
+            "Float",
+            "Int",
+            "String")
+        );
+
+        customPrimitives = new HashSet<>(
+          Arrays.asList(
+            "Byte",
+            "DateOnly",
+            "DateTime")
+        );
+
+        instantiationTypes.clear();
+
+        typeMapping.clear();
+        typeMapping.put("integer", "Int");
+        typeMapping.put("long", "Int");
+        typeMapping.put("number", "Float");
+        typeMapping.put("float", "Float");
+        typeMapping.put("double", "Float");
+        typeMapping.put("boolean", "Bool");
+        typeMapping.put("string", "String");
+        typeMapping.put("array", "List");
+        typeMapping.put("date", "DateOnly");
+        typeMapping.put("DateTime", "DateTime");
+        typeMapping.put("password", "String");
+        typeMapping.put("file", "String");
+        typeMapping.put("ByteArray", "Byte");
+        typeMapping.put("binary", "String");
+
+        importMapping.clear();
+
+        cliOptions.clear();
+
+        supportingFiles.add(new SupportingFile("Byte.mustache", "src", "Byte.elm"));
+        supportingFiles.add(new SupportingFile("DateOnly.mustache", "src", "DateOnly.elm"));
+        supportingFiles.add(new SupportingFile("DateTime.mustache", "src", "DateTime.elm"));
+        supportingFiles.add(new SupportingFile("Main.mustache", "src", "Main.elm"));
+        supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
+        supportingFiles.add(new SupportingFile("elm-package.mustache", "", "elm-package.json"));
+        supportingFiles.add(new SupportingFile("gitignore.mustache", "", ".gitignore"));
+    }
+
+    @Override
+    public String escapeUnsafeCharacters(String input) {
+        return input.replace("*/", "*_/").replace("/*", "/_*");
+    }
+
+    @Override
+    public String escapeQuotationMark(String input) {
+        return input.replace("\"", "");
+    }
+
+    @Override
+    public String toApiName(String name) {
+        if (name.length() == 0) {
+            return "Default";
+        }
+        return initialCaps(name);
+    }
+
+    @Override
+    public String toModelName(String name) {
+        return camelize(name);
+    }
+
+    @Override
+    public String toModelFilename(String name) {
+        return toModelName(name);
+    }
+
+    @Override
+    public String toEnumName(CodegenProperty property) {
+        return toModelName(property.name);
+    }
+
+    @Override
+    public String toVarName(String name) {
+        final String varName = camelize(name, true);
+        return isReservedWord(varName) ? escapeReservedWord(name) : varName;
+    }
+
+    @Override
+    public String toEnumVarName(String value, String datatype) {
+        final String camelized = camelize(value.replace(" ", "_").replace("(", "_").replace(")", "")); // TODO FIXME escape properly
+        if (!Character.isUpperCase(camelized.charAt(0))) {
+            return "N" + camelized;
+        }
+        return camelized;
+    }
+
+    @Override
+    public String escapeReservedWord(String name) {
+        return name + "_";
+    }
+
+    @Override
+    public String apiFileFolder() {
+        return outputFolder + "/src/Request/" + apiPackage().replace('.', File.separatorChar);
+    }
+
+    @Override
+    public String modelFileFolder() {
+        return outputFolder + "/src/Data/" + modelPackage().replace('.', File.separatorChar);
+    }
+
+    @SuppressWarnings({ "static-method", "unchecked" })
+    public Map<String, Object> postProcessAllModels(Map<String, Object> objs) {
+        // Index all CodegenModels by model name.
+        Map<String, CodegenModel> allModels = new HashMap<>();
+        for (Map.Entry<String, Object> entry : objs.entrySet()) {
+            String modelName = toModelName(entry.getKey());
+            Map<String, Object> inner = (Map<String, Object>) entry.getValue();
+            List<Map<String, Object>> models = (List<Map<String, Object>>) inner.get("models");
+            for (Map<String, Object> mo : models) {
+                CodegenModel cm = (CodegenModel) mo.get("model");
+                allModels.put(modelName, cm);
+            }
+        }
+        // Let parent know about all its children
+        for (CodegenModel cm : allModels.values()) {
+            CodegenModel parent = allModels.get(cm.parent);
+
+            if (parent != null) {
+                if (parent.children == null) {
+                    parent.children = new ArrayList<>();
+                    parent.hasChildren = true;
+                }
+                parent.children.add(cm);
+                Collections.sort(parent.children, new Comparator<CodegenModel>() {
+                    @Override
+                    public int compare(CodegenModel cm1, CodegenModel cm2) {
+                        return Collator.getInstance().compare(cm1.classname, cm2.classname);
+                    }
+                });
+            }
+        }
+        for (Map.Entry<String, Object> entry : objs.entrySet()) {
+            Map<String, Object> inner = (Map<String, Object>) entry.getValue();
+            List<Map<String, Object>> models = (List<Map<String, Object>>) inner.get("models");
+            for (Map<String, Object> mo : models) {
+                CodegenModel cm = (CodegenModel) mo.get("model");
+                if (cm.isEnum) {
+                    this.addEncoderAndDecoder(cm.vendorExtensions, cm.classname, false);
+                    cm.vendorExtensions.put(X_UNION_TYPE, cm.classname);
+                } else if (cm.isAlias) {
+                    this.addEncoderAndDecoder(cm.vendorExtensions, cm.dataType, true);
+                }
+
+                List<ElmImport> elmImports = new ArrayList<>();
+                for (CodegenProperty property : cm.allVars) {
+                    if (property.complexType != null) {
+                        elmImports.add(createPropertyImport(property));
+                    }
+                }
+                if (cm.discriminator != null) {
+                    for (CodegenModel child : cm.children) {
+                        // add child imports
+                        final ElmImport elmImport = new ElmImport();
+                        final String modulePrefix = customPrimitives.contains(child.classname) ? "" : "Data.";
+                        elmImport.moduleName = modulePrefix + child.classname;
+                        elmImport.exposures = new TreeSet<>();
+                        elmImport.exposures.add(child.classname);
+                        elmImport.exposures.add(child.classVarName + "Decoder");
+                        elmImport.exposures.add(child.classVarName + "Encoder");
+                        elmImport.hasExposures = true;
+                        elmImports.add(elmImport);
+
+                        // set discriminator value to all children (recursively)
+                        this.setDiscriminatorValue(child, cm.discriminator, this.getDiscriminatorValue(child));
+
+                        // add all non-discriminator vars
+                        int index = 0;
+                        for (CodegenProperty property : cm.vars) {
+                            if (!cm.discriminator.equals(property.baseName)) {
+                                child.vars.add(index++, property);
+                            }
+                        }
+                    }
+                }
+                inner.put("elmImports", elmImports);
+            }
+        }
+        return objs;
+    }
+
+    private void setDiscriminatorValue(CodegenModel model, String baseName, String value) {
+        for (CodegenProperty prop : model.vars) {
+            if (prop.baseName.equals(baseName)) {
+                prop.discriminatorValue = value;
+            }
+        }
+        for (CodegenProperty prop : model.allVars) {
+            if (prop.baseName.equals(baseName)) {
+                prop.discriminatorValue = value;
+            }
+        }
+        if (model.children != null) {
+            final boolean newDiscriminator = model.discriminator != null;
+            for (CodegenModel child : model.children) {
+                this.setDiscriminatorValue(child, baseName, newDiscriminator ? value : this.getDiscriminatorValue(child));
+            }
+        }
+    }
+
+    private String getDiscriminatorValue(CodegenModel model) {
+        return model.vendorExtensions.containsKey(X_DISCRIMINATOR_TYPE) ?
+          (String) model.vendorExtensions.get(X_DISCRIMINATOR_TYPE) : model.classname;
+    }
+
+    private ElmImport createPropertyImport(final CodegenProperty property) {
+        final ElmImport elmImport = new ElmImport();
+        final String modulePrefix = customPrimitives.contains(property.complexType) ? "" : "Data.";
+        elmImport.moduleName = modulePrefix + property.complexType;
+        elmImport.exposures = new TreeSet<>();
+        elmImport.exposures.add(property.complexType);
+        if (property.vendorExtensions.containsKey(X_DECODER)) {
+            elmImport.exposures.add((String) property.vendorExtensions.get(X_DECODER));
+        }
+        if (property.vendorExtensions.containsKey(X_ENCODER)) {
+            elmImport.exposures.add((String) property.vendorExtensions.get(X_ENCODER));
+        }
+        elmImport.hasExposures = true;
+        return elmImport;
+    }
+
+    @Override
+    public Map<String, Object> postProcessModels(Map<String, Object> objs) {
+        return postProcessModelsEnum(objs);
+    }
+
+    @Override
+    @SuppressWarnings({ "static-method", "unchecked" })
+    public Map<String, Object> postProcessOperations(Map<String, Object> operations) {
+        Map<String, Object> objs = (Map<String, Object>) operations.get("operations");
+        List<CodegenOperation> ops = (List<CodegenOperation>) objs.get("operation");
+
+        Map<String, Set<String>> dependencies = new HashMap<>();
+
+        for (CodegenOperation op : ops) {
+            String path = op.path;
+            for (CodegenParameter param : op.pathParams) {
+              final String var = param.isString ? param.paramName : "toString " + param.paramName;
+                path = path.replace("{" + param.paramName + "}", "\" ++ " + var + " ++ \"");
+            }
+            op.path = ("\"" + path + "\"").replaceAll(" \\+\\+ \"\"", "");
+
+            if (op.bodyParam != null) {
+                final String encoder = (String) op.bodyParam.vendorExtensions.get(X_ENCODER);
+                if (encoder != null) {
+                    if (!dependencies.containsKey(op.bodyParam.dataType)) {
+                        dependencies.put(op.bodyParam.dataType, new TreeSet<String>());
+                    }
+                    dependencies.get(op.bodyParam.dataType).add(encoder);
+                }
+            }
+            for (CodegenResponse resp : op.responses) {
+                final String decoder = (String) resp.vendorExtensions.get(X_DECODER);
+                if (decoder != null) {
+                    if (!dependencies.containsKey(resp.dataType)) {
+                        dependencies.put(resp.dataType, new TreeSet<String>());
+                    }
+                    dependencies.get(resp.dataType).add(decoder);
+                }
+            }
+        }
+
+        List<ElmImport> elmImports = new ArrayList<>();
+        for (Map.Entry<String, Set<String>> entry : dependencies.entrySet()) {
+            final ElmImport elmImport = new ElmImport();
+            final String key = entry.getKey();
+            elmImport.moduleName = "Data." + key;
+            elmImport.exposures = entry.getValue();
+            elmImport.exposures.add(key);
+            elmImport.hasExposures = true;
+            elmImports.add(elmImport);
+        }
+        operations.put("elmImports", elmImports);
+
+        return operations;
+    }
+
+    @Override
+    public String toDefaultValue(Property p) {
+        if (p instanceof StringProperty) {
+            StringProperty sp = (StringProperty) p;
+            if (sp.getDefault() != null) {
+                return toOptionalValue("\"" + sp.getDefault().toString() + "\"");
+            }
+            return toOptionalValue(null);
+        } else if (p instanceof BooleanProperty) {
+            BooleanProperty bp = (BooleanProperty) p;
+            if (bp.getDefault() != null) {
+                return toOptionalValue(bp.getDefault() ? "True" : "False");
+            }
+            return toOptionalValue(null);
+        } else if (p instanceof DateProperty) {
+            return toOptionalValue(null);
+        } else if (p instanceof DateTimeProperty) {
+            return toOptionalValue(null);
+        } else if (p instanceof DoubleProperty) {
+            DoubleProperty dp = (DoubleProperty) p;
+            if (dp.getDefault() != null) {
+                return toOptionalValue(dp.getDefault().toString());
+            }
+            return toOptionalValue(null);
+        } else if (p instanceof FloatProperty) {
+            FloatProperty fp = (FloatProperty) p;
+            if (fp.getDefault() != null) {
+                return toOptionalValue(fp.getDefault().toString());
+            }
+            return toOptionalValue(null);
+        } else if (p instanceof IntegerProperty) {
+            IntegerProperty ip = (IntegerProperty) p;
+            if (ip.getDefault() != null) {
+                return toOptionalValue(ip.getDefault().toString());
+            }
+            return toOptionalValue(null);
+        } else if (p instanceof LongProperty) {
+            LongProperty lp = (LongProperty) p;
+            if (lp.getDefault() != null) {
+                return toOptionalValue(lp.getDefault().toString());
+            }
+            return toOptionalValue(null);
+        } else {
+            return toOptionalValue(null);
+        }
+    }
+    
+    private String toOptionalValue(String value) {
+        if (value == null) {
+            return "Nothing";
+        }
+        return "(Just " + value + ")";
+    }
+
+    @Override
+    public String getSwaggerType(Property p) {
+        String swaggerType = super.getSwaggerType(p);
+        String type;
+        if (typeMapping.containsKey(swaggerType)) {
+            type = typeMapping.get(swaggerType);
+            if (languageSpecificPrimitives.contains(type)) {
+                return type;
+            }
+        } else
+            type = swaggerType;
+        return toModelName(type);
+    }
+
+    @Override
+    public String getTypeDeclaration(Property p) {
+        if (p instanceof ArrayProperty) {
+            ArrayProperty ap = (ArrayProperty) p;
+            Property inner = ap.getItems();
+            return getTypeDeclaration(inner);
+        } else if (p instanceof MapProperty) {
+            MapProperty mp = (MapProperty) p;
+            Property inner = mp.getAdditionalProperties();
+            return getTypeDeclaration(inner);
+        }
+        return super.getTypeDeclaration(p);
+    }
+
+    @Override
+    public CodegenProperty fromProperty(String name, Property p) {
+        final CodegenProperty property = super.fromProperty(name, p);
+
+        final String dataType = property.isEnum ? property.baseName : property.datatype;
+        addEncoderAndDecoder(property.vendorExtensions, dataType, property.isPrimitiveType && !property.isEnum);
+        if (property.isEnum) {
+            property.vendorExtensions.put(X_UNION_TYPE, property.datatypeWithEnum);
+        }
+
+        return property;
+    }
+
+    @Override
+    public CodegenResponse fromResponse(String responseCode, Response resp) {
+        final CodegenResponse response = super.fromResponse(responseCode, resp);
+        if (response.dataType != null) {
+            addEncoderAndDecoder(response.vendorExtensions, response.dataType, response.primitiveType);
+        }
+        return response;
+    }
+
+    @Override
+    public CodegenParameter fromParameter(Parameter param, Set<String> imports) {
+        final CodegenParameter parameter = super.fromParameter(param, imports);
+        addEncoderAndDecoder(parameter.vendorExtensions, parameter.dataType, parameter.isPrimitiveType);
+        return parameter;
+    }
+
+    private void addEncoderAndDecoder(Map<String, Object> vendorExtensions, String dataType, Boolean isPrimitiveType) {
+        final String baseName = camelize(dataType, true);
+        String encoderName;
+        String decoderName;
+        if (isPrimitiveType) {
+            encoderName = "Encode." + baseName;
+            decoderName = "Decode." + baseName;
+        } else {
+            encoderName = baseName + "Encoder";
+            decoderName = baseName + "Decoder";
+        }
+        if (!vendorExtensions.containsKey(X_ENCODER)) {
+            vendorExtensions.put(X_ENCODER, encoderName);
+        }
+        if (!vendorExtensions.containsKey(X_DECODER)) {
+            vendorExtensions.put(X_DECODER, decoderName);
+        }
+    }
+
+    private static class ElmImport {
+        public String moduleName;
+        public String as;
+        public Set<String> exposures;
+        public Boolean hasExposures;
+    }
+}

modules/swagger-codegen/src/main/resources/META-INF/services/io.swagger.codegen.CodegenConfig

@@ -12,6 +12,7 @@ io.swagger.codegen.languages.CppRestClientCodegen
 io.swagger.codegen.languages.CsharpDotNet2ClientCodegen
 io.swagger.codegen.languages.DartClientCodegen
 io.swagger.codegen.languages.ElixirClientCodegen
+io.swagger.codegen.languages.ElmClientCodegen
 io.swagger.codegen.languages.EiffelClientCodegen
 io.swagger.codegen.languages.ErlangClientCodegen
 io.swagger.codegen.languages.ErlangServerCodegen

modules/swagger-codegen/src/main/resources/elm/Byte.mustache

@@ -0,0 +1,18 @@
+module Byte exposing (Byte, byteDecoder, byteEncoder)
+
+import Json.Decode as Decode exposing (Decoder)
+import Json.Encode as Encode
+
+
+type alias Byte = String
+
+
+byteDecoder : Decoder Byte
+byteDecoder =
+    Decode.string
+
+
+byteEncoder : Byte -> Encode.Value
+byteEncoder model =
+    Encode.string model
+

modules/swagger-codegen/src/main/resources/elm/DateOnly.mustache

@@ -0,0 +1,34 @@
+module DateOnly exposing (DateOnly, dateOnlyDecoder, dateOnlyEncoder)
+
+import Date
+import Date.Extra exposing (fromIsoString, toFormattedString)
+import Json.Decode as Decode exposing (Decoder)
+import Json.Encode as Encode
+
+
+type alias DateOnly =
+    Date.Date
+
+
+dateOnlyDecoder : Decoder DateOnly
+dateOnlyDecoder =
+    Decode.string
+        |> Decode.andThen decodeIsoString
+
+
+dateOnlyEncoder : DateOnly -> Encode.Value
+dateOnlyEncoder model =
+    Encode.string <| toFormattedString "yyyy-MM-dd" model
+
+
+decodeIsoString : String -> Decoder DateOnly
+decodeIsoString str =
+    case fromIsoString str of
+        Just date ->
+            Decode.succeed date
+
+        Nothing ->
+            Decode.fail <|
+                "Cannot convert "
+                    ++ str
+                    ++ " to DateOnly"

modules/swagger-codegen/src/main/resources/elm/DateTime.mustache

@@ -0,0 +1,34 @@
+module DateTime exposing (DateTime, dateTimeDecoder, dateTimeEncoder)
+
+import Date
+import Date.Extra exposing (fromIsoString, toIsoString)
+import Json.Decode as Decode exposing (Decoder)
+import Json.Encode as Encode
+
+
+type alias DateTime =
+    Date.Date
+
+
+dateTimeDecoder : Decoder DateTime
+dateTimeDecoder =
+    Decode.string
+        |> Decode.andThen decodeIsoString
+
+
+dateTimeEncoder : DateTime -> Encode.Value
+dateTimeEncoder model =
+    Encode.string <| toIsoString model
+
+
+decodeIsoString : String -> Decoder DateTime
+decodeIsoString str =
+    case fromIsoString str of
+        Just date ->
+            Decode.succeed date
+
+        Nothing ->
+            Decode.fail <|
+                "Cannot convert "
+                    ++ str
+                    ++ " to DateTime"

modules/swagger-codegen/src/main/resources/elm/Main.mustache

@@ -0,0 +1,43 @@
+module Main exposing (..)
+
+import Json.Decode as Decode
+import Html exposing (Html, button, div, text)
+import Html.Events exposing (onClick)
+import Http
+
+
+main : Program Never Model Msg
+main =
+    Html.program
+        { init = init
+        , view = view
+        , update = update
+        , subscriptions = subscriptions
+        }
+
+type alias Model =
+    { status : Maybe Int
+    }
+
+init : (Model, Cmd Msg)
+init =
+    ( Model Nothing, Cmd.none )
+
+type Msg
+    = NoOp
+
+update : Msg -> Model -> (Model, Cmd Msg)
+update msg model =
+    case msg of
+        NoOp
+            ( model, Cmd.none )
+
+
+view : Model -> Html Msg
+view model =
+    Html.text "main"
+
+
+subscriptions : Model -> Sub Msg
+subscriptions model =
+    Sub.none

modules/swagger-codegen/src/main/resources/elm/README.mustache

@@ -0,0 +1,18 @@
+# Elm API client
+
+{{#appDescription}}
+{{{appDescription}}}
+{{/appDescription}}
+
+## Overview
+This API client was generated by the [swagger-codegen](https://github.com/swagger-api/swagger-codegen) project. By using the [swagger-spec](https://github.com/swagger-api/swagger-spec) from a remote server, you can easily generate an API client.
+
+- API version: {{appVersion}}
+- Package version: {{packageVersion}}
+{{^hideGenerationTimestamp}}
+- Build date: {{generatedDate}}
+{{/hideGenerationTimestamp}}
+- Build package: {{generatorClass}}
+{{#infoUrl}}
+For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
+{{/infoUrl}}

modules/swagger-codegen/src/main/resources/elm/aliasDecoder.mustache

@@ -0,0 +1,5 @@
+{{classVarName}}Decoder : Decoder {{classname}}
+{{classVarName}}Decoder =
+    decode {{classname}}
+{{#allVars}}{{^discriminatorValue}}        |> {{>fieldDecoder}}
+{{/discriminatorValue}}{{/allVars}}

modules/swagger-codegen/src/main/resources/elm/aliasEncoder.mustache

@@ -0,0 +1,7 @@
+{{classVarName}}Encoder : {{classname}} -> Encode.Value
+{{classVarName}}Encoder model =
+    Encode.object
+{{#allVars}}
+        {{#-first}}[{{/-first}}{{^-first}},{{/-first}} {{>fieldEncoder}}
+{{/allVars}}
+        ]

modules/swagger-codegen/src/main/resources/elm/api.mustache

@@ -0,0 +1,33 @@
+{{>licenseInfo}}
+
+module Request.{{classname}} exposing ({{#operations}}{{#operation}}{{^-first}}, {{/-first}}{{operationId}}{{/operation}}{{/operations}})
+
+{{>imports}}import Http
+import Json.Decode as Decode
+
+
+basePath : String
+basePath =
+    "{{basePath}}"
+
+
+{{#operations}}
+  {{#operation}}
+{-
+   {{notes}}
+-}
+{{operationId}} : {{#pathParams}}{{dataType}} -> {{/pathParams}}{{#bodyParam}}{{dataType}} -> {{/bodyParam}}Http.Request {{#responses}}{{#-first}}{{^dataType}}(){{/dataType}}{{#isListContainer}}(List {{/isListContainer}}{{dataType}}{{#isListContainer}}){{/isListContainer}}{{/-first}}{{/responses}}
+{{operationId}} {{#pathParams}}{{paramName}} {{/pathParams}}{{#bodyParam}}model {{/bodyParam}}=
+    { method = "{{httpMethod}}"
+    , url = basePath ++ {{{path}}}
+    , headers = []
+    , body = {{#bodyParam}}Http.jsonBody <| {{vendorExtensions.x-encoder}} model{{/bodyParam}}{{^bodyParam}}Http.emptyBody{{/bodyParam}}
+    , expect = {{#responses}}{{#-first}}{{^dataType}}Http.expectStringResponse (\_ -> Ok ()){{/dataType}}{{#dataType}}Http.expectJson {{#isListContainer}}(Decode.list {{/isListContainer}}{{#vendorExtensions}}{{x-decoder}}{{/vendorExtensions}}{{#isListContainer}}){{/isListContainer}}{{/dataType}}{{/-first}}{{/responses}}
+    , timeout = Just 30000
+    , withCredentials = False
+    }
+        |> Http.request
+
+
+  {{/operation}}
+{{/operations}}

modules/swagger-codegen/src/main/resources/elm/elm-package.mustache

@@ -0,0 +1,18 @@
+{
+    "version": "1.0.0",
+    "summary": "helpful summary of your project, less than 80 characters",
+    "repository": "https://github.com/user/project.git",
+    "license": "BSD3",
+    "source-directories": [
+        "src"
+    ],
+    "exposed-modules": [],
+    "dependencies": {
+        "NoRedInk/elm-decode-pipeline": "3.0.0 <= v < 4.0.0",
+        "elm-lang/core": "5.1.1 <= v < 6.0.0",
+        "elm-lang/html": "2.0.0 <= v < 3.0.0",
+        "elm-lang/http": "1.0.0 <= v < 2.0.0",
+        "justinmimbs/elm-date-extra": "2.0.3 <= v < 3.0.0"
+    },
+    "elm-version": "0.18.0 <= v < 0.19.0"
+}

modules/swagger-codegen/src/main/resources/elm/fieldDecoder.mustache

@@ -0,0 +1 @@
+{{#required}}required{{/required}}{{^required}}optional{{/required}} "{{baseName}}" {{^required}}(Decode.nullable {{/required}}{{#isContainer}}(Decode.list {{/isContainer}}{{vendorExtensions.x-decoder}}{{#isContainer}}){{/isContainer}}{{^required}}){{/required}}{{^required}} {{{defaultValue}}}{{/required}}

modules/swagger-codegen/src/main/resources/elm/fieldEncoder.mustache

@@ -0,0 +1 @@
+( "{{baseName}}", {{#discriminatorValue}}Encode.string "{{discriminatorValue}}"{{/discriminatorValue}}{{^discriminatorValue}}{{^required}}withDefault Encode.null (map {{/required}}{{#isContainer}}(Encode.list << List.map {{/isContainer}}{{vendorExtensions.x-encoder}}{{#isContainer}}){{/isContainer}} model.{{name}}{{^required}}){{/required}}{{/discriminatorValue}} )

modules/swagger-codegen/src/main/resources/elm/gitignore.mustache

@@ -0,0 +1 @@
+/elm-stuff

modules/swagger-codegen/src/main/resources/elm/imports.mustache

@@ -0,0 +1,3 @@
+{{#elmImports}}
+import {{moduleName}}{{#as}} as {{as}}{{/as}}{{#hasExposures}} exposing ({{#exposures}}{{^-first}}, {{/-first}}{{.}}{{/exposures}}){{/hasExposures}}
+{{/elmImports}}

modules/swagger-codegen/src/main/resources/elm/licenseInfo.mustache

@@ -0,0 +1,11 @@
+{-
+   {{{appName}}}
+   {{{appDescription}}}
+
+   {{#version}}OpenAPI spec version: {{{version}}}{{/version}}
+   {{#infoEmail}}Contact: {{{infoEmail}}}{{/infoEmail}}
+
+   NOTE: This file is auto generated by the swagger code generator program.
+   https://github.com/swagger-api/swagger-codegen.git
+   Do not edit this file manually.
+-}

modules/swagger-codegen/src/main/resources/elm/model.mustache

@@ -0,0 +1,24 @@
+{{>licenseInfo}}
+
+module Data.{{classname}} exposing ({{#models}}{{#model}}{{classname}}{{#hasChildren}}(..){{/hasChildren}}{{#isEnum}}(..){{/isEnum}}{{^isEnum}}{{#vars}}{{#isEnum}}, {{vendorExtensions.x-union-type}}(..){{/isEnum}}{{/vars}}{{/isEnum}}, {{classVarName}}Decoder, {{classVarName}}Encoder{{/model}}{{/models}})
+
+{{>imports}}import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Pipeline exposing (decode, optional, required)
+import Json.Encode as Encode
+import Maybe exposing (map, withDefault)
+
+
+{{#models}}
+{{#model}}
+{{#description}}
+{-
+   {{{description}}}
+-}
+{{/description}}
+{{#isEnum}}{{>modelTypeUnion}}{{/isEnum}}{{^isEnum}}{{#hasChildren}}{{>modelTypeDiscriminator}}{{/hasChildren}}{{^hasChildren}}{{#isAlias}}{{>modelTypePrimitive}}{{/isAlias}}{{^isAlias}}{{>modelTypeAlias}}{{/isAlias}}{{/hasChildren}}{{/isEnum}}
+{{/model}}
+{{^-last}}
+
+
+{{/-last}}
+{{/models}}

modules/swagger-codegen/src/main/resources/elm/modelTypeAlias.mustache

@@ -0,0 +1,28 @@
+
+
+type alias {{classname}} =
+    { {{#vars}}{{^-first}}    , {{/-first}}{{name}} : {{^required}}Maybe {{/required}}{{#isContainer}}(List {{/isContainer}}{{#isEnum}}{{nameInCamelCase}}{{/isEnum}}{{^isEnum}}{{datatype}}{{/isEnum}}{{#isContainer}}){{/isContainer}}
+{{/vars}}    }
+{{#vars}}
+{{#isEnum}}
+
+
+{{>union}}
+{{/isEnum}}
+{{/vars}}
+
+
+{{>aliasDecoder}}
+
+
+{{>aliasEncoder}}
+{{#vars}}
+{{#isEnum}}
+
+
+{{>unionDecoder}}
+
+
+{{>unionEncoder}}
+{{/isEnum}}
+{{/vars}}

modules/swagger-codegen/src/main/resources/elm/modelTypeDiscriminator.mustache

@@ -0,0 +1,34 @@
+type {{classname}}
+{{#children}}
+    {{#-first}}={{/-first}}{{^-first}}|{{/-first}} {{classname}}Type {{classname}}
+{{/children}}
+
+
+{{classVarName}}Decoder : Decoder {{classname}}
+{{classVarName}}Decoder =
+    Decode.field "{{discriminator}}" Decode.string
+        |> Decode.andThen {{classVarName}}TypeDecoder
+
+
+{{classVarName}}TypeDecoder : String -> Decoder {{classname}}
+{{classVarName}}TypeDecoder {{discriminator}} =
+    case {{discriminator}} of
+{{#children}}
+        "{{vendorExtensions.x-discriminator-value}}" ->
+            Decode.map {{classname}}Type {{classVarName}}Decoder
+
+{{/children}}
+        _ ->
+            Decode.fail <|
+                "Trying to decode {{classname}}, but {{discriminator}} "
+                ++ toString {{discriminator}} ++ " is not supported."
+
+
+{{classVarName}}Encoder : {{classname}} -> Encode.Value
+{{classVarName}}Encoder model =
+    case model of
+{{#children}}
+        {{classname}}Type subModel ->
+            {{classVarName}}Encoder subModel
+
+{{/children}}

modules/swagger-codegen/src/main/resources/elm/modelTypePrimitive.mustache

@@ -0,0 +1,14 @@
+
+
+type alias {{classname}}
+    = {{dataType}}
+
+
+{{classVarName}}Decoder : Decoder {{classname}}
+{{classVarName}}Decoder =
+    {{vendorExtensions.x-decoder}}
+
+
+{{classVarName}}Encoder : {{classname}} -> Encode.Value
+{{classVarName}}Encoder =
+    {{vendorExtensions.x-encoder}}

modules/swagger-codegen/src/main/resources/elm/modelTypeUnion.mustache

@@ -0,0 +1,7 @@
+{{>union}}
+
+
+{{>unionDecoder}}
+
+
+{{>unionEncoder}}

modules/swagger-codegen/src/main/resources/elm/union.mustache

@@ -0,0 +1,6 @@
+type {{#vendorExtensions}}{{x-union-type}}{{/vendorExtensions}}
+{{#allowableValues}}
+  {{#enumVars}}
+    {{#-first}}={{/-first}}{{^-first}}|{{/-first}} {{name}}
+  {{/enumVars}}
+{{/allowableValues}}

modules/swagger-codegen/src/main/resources/elm/unionDecoder.mustache

@@ -0,0 +1,15 @@
+{{vendorExtensions.x-decoder}} : Decoder {{vendorExtensions.x-union-type}}
+{{vendorExtensions.x-decoder}} =
+    Decode.string
+        |> Decode.andThen (\str ->
+            case str of
+{{#allowableValues}}
+{{#enumVars}}
+                {{{value}}} ->
+                    Decode.succeed {{name}}
+
+{{/enumVars}}
+{{/allowableValues}}
+                other ->
+                    Decode.fail <| "Unknown type: " ++ other
+        )

modules/swagger-codegen/src/main/resources/elm/unionEncoder.mustache

@@ -0,0 +1,10 @@
+{{vendorExtensions.x-encoder}} : {{vendorExtensions.x-union-type}} -> Encode.Value
+{{vendorExtensions.x-encoder}} model =
+    case model of
+{{#allowableValues}}
+{{#enumVars}}
+        {{name}} ->
+            Encode.string {{{value}}}
+
+{{/enumVars}}
+{{/allowableValues}}