Just a simple numerical integration in WebAssembly. Why? Why not!

integration.wat

(module
  (func $f (param $x f32) (result f32)
    ;;function f(x) = x^2
    get_local $x
    get_local $x
    f32.mul
  )

  (func (export "integrate") (param $ss f32) (param $start f32) (param $end f32) (result f32)
    (local $sum f32)
    (local $idx f32)
    
    f32.const 0
    set_local $sum

    get_local $start
    set_local $idx

    loop $integration
      ;; evaluate f at the current index
      get_local $idx
      call $f

      ;; add the result to the running sum
      get_local $ss
      f32.mul

      get_local $sum
      f32.add
      set_local $sum

      ;; increment the index
      get_local $ss
      get_local $idx
      f32.add
      set_local $idx

      ;; break if we reached the end of the range
      get_local $end      
      get_local $idx
      f32.gt
      br_if $integration
    end

    get_local $sum)
)