diff --git a/src/Model.re b/src/Model.re
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+++ b/src/Model.re
@@ -0,0 +1,68 @@
+module IOTypes = {
+  type singleChoice = {options: list(string)};
+  type floatPoint = {validatations: list(float => bool)};
+  type withDefault('a) = {default: option('a)};
+};
+
+module Input = {
+  type parameterType =
+    | Year(IOTypes.withDefault(float))
+    | SingleChoice(IOTypes.singleChoice)
+    | FloatPoint
+    | FloatCdf;
+
+  type parameter = {
+    name: string,
+    parameterType,
+  };
+
+  let make = (name, parameterType) => {name, parameterType};
+};
+
+module Output = {
+  type parameterType =
+    | Year
+    | SingleChoice(IOTypes.singleChoice)
+    | FloatPoint
+    | FloatCdf;
+
+  type parameter = {
+    name: string,
+    parameterType,
+  };
+
+  let make = (name, parameterType) => {name, parameterType};
+};
+
+type props = {
+  name: string,
+  author: string,
+  assumptions: list(Input.parameter),
+  inputs: list(Input.parameter),
+  outputs: list(Output.parameter),
+};
+
+let model1 = {
+  name: "Calculate the payments and payouts of EA Funds based on existing data.",
+  author: "George Harrison",
+  assumptions: [Input.make("Yearly Growth Rate", FloatPoint)],
+  inputs: [
+    Input.make(
+      "Fund",
+      SingleChoice({
+        options: [
+          "Animal Welfare Fund",
+          "Global Health Fund",
+          "Long Term Future Fund",
+          "Meta Fund",
+          "Total",
+        ],
+      }),
+    ),
+    {name: "Year", parameterType: Year({default: Some(2030.0)})},
+  ],
+  outputs: [
+    Output.make("Payments", FloatCdf),
+    Output.make("Payouts", FloatCdf),
+  ],
+};
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