Nomad

A CLI calculator application written in Haskell. This project is a continued version of https://github.com/dhansmair/nomad-calculator (university project). It's a learning project that explores functional programming in Haskell, but also other topics such as parsing, the lambda calculus and basic type inference.

Features of nomad:

• evaluate common arithmetic expressions
• Definition of variables and (mathematical) functions
• Partial function application
• higher-order functions
• Builtin functions such as sin, cos, tan, log, exp etc.
• Builtin derive, which returns the derivative of a function of type num -> num.

Features that would be nice (but will probably not come):

• automatic simplification of terms and functions
• boolean type
• loading / executing code from file
• useful type error messages

Setup

stack build                 // builds all executables
stack run cli               // runs cli executable

Syntax

x = expr                    // define global variable
f(x,y) = expr               // define function
f = \x,y -> expr            // equivalently, functions can be defined as abstractions
expr                        // evaluate expressions
(\x -> 2*x)(4)              // lambda application
f(1,2)                      // function application

expressions can be:

1                           // any number
x                           // a variable
1 + 2 / 3 etc               // binary operations
f(x)                        // function call
(\x,y->x*y)(5,3)            // application of an abstraction

Commands

:q                  close the cli
:t <expr>           show the type of an expression
:env                show the current environment (stored functions and variables)