Hackathon tasks - 3

[nponeccop]

• [ ] Use st ^. https://github.com/ptol/oczor/blob/master/src/Oczor/Compiler/Compiler.hs#L100
• [x] Use patterns: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/CodeGenAst.hs#L52
• [x] Use . and <$>: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L33
• [x] Use $: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L44
• [x] Replace with case: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L108
• [x] Inline instances: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L112
• [ ] Change arguments order to eta-reduce: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L130
• [x] Use >>=: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L177
• [x] Use case and move return out: https://github.com/ptol/oczor/blob/master/src/Oczor/Converter/Converter.hs#L407
• [x] Use liftA2: https://github.com/ptol/oczor/blob/master/src/Oczor/Infer/Infer.hs#L18