{def eulersMethod
 {def eulersMethod.r
  {lambda {:f :b :h :t :y}
   {if {<= :t :b}
    then {tr {td :t} {td {/ {round {* :y 1000}} 1000}}}
         {eulersMethod.r :f :b :h {+ :t :h} {+ :y {* :h {:f :t :y}}}}
    else}}}
 {lambda {:f :y0 :a :b :h}
  {table {eulersMethod.r :f :b :h :a :y0}}}}

{def cooling
 {lambda {:time :temp}
  {* -0.07 {- :temp 20}}}}

{eulersMethod cooling 100 0 100 10}
->
 0 	100
 10 	44
 20 	27.2
 30 	22.16
 40 	20.648
 50 	20.194
 60 	20.058
 70 	20.017
 80 	20.005
 90 	20.002
 100 	20