Allow setting cabal version too

src/installer.ts

@@ -17,10 +17,16 @@ export async function cacheHaskellTool(installDir: string, tool: string) {
 }
 
 export async function findHaskellGHCVersion(version: string) {
+  if (!version) {
+    version = '8.6.5';
+  }
   return _findHaskellToolVersion('ghc', version);
 }
 
 export async function findHaskellCabalVersion(version: string) {
+  if (!version) {
+    version = '3.0';
+  }
   return _findHaskellToolVersion('cabal', version);
 }
 

src/setup-haskell.ts

@@ -1,5 +1,9 @@
 import * as core from '@actions/core';
-import {findHaskellGHCVersion, cacheHaskellTool} from './installer';
+import {
+  findHaskellGHCVersion,
+  findHaskellCabalVersion,
+  cacheHaskellTool
+} from './installer';
 
 async function run() {
   try {
@@ -7,6 +11,9 @@ async function run() {
     await cacheHaskellTool('/opt', 'cabal');
     let ghcVersion = core.getInput('ghc-version');
     await findHaskellGHCVersion(ghcVersion);
+
+    let cabalVersion = core.getInput('cabal-version');
+    await findHaskellCabalVersion(cabalVersion);
   } catch (error) {
     core.setFailed(error.message);
   }