diff --git a/include/evalhyd/evald.hpp b/include/evalhyd/evald.hpp
index 7ae018e12ae57a0b5b337c0f8d78898b37895fa7..34a879f00cdd235fd14f78297e70ee4bec84a0fe 100644
--- a/include/evalhyd/evald.hpp
+++ b/include/evalhyd/evald.hpp
@@ -1,21 +1,12 @@
-#ifndef EVALHYD_DETERMINIST_HPP
-#define EVALHYD_DETERMINIST_HPP
+#ifndef EVALHYD_EVALD_HPP
+#define EVALHYD_EVALD_HPP
 
 #include <unordered_map>
 #include <vector>
-#include <array>
-#include <stdexcept>
+
 #include <xtensor/xexpression.hpp>
 #include <xtensor/xarray.hpp>
-#include <xtensor/xscalar.hpp>
-
-#include "../../src/utils.hpp"
-#include "../../src/masks.hpp"
-#include "../../src/maths.hpp"
-#include "../../src/uncertainty.hpp"
-#include "../../src/determinist/evaluator.hpp"
 
-namespace eh = evalhyd;
 
 namespace evalhyd
 {
@@ -158,239 +149,7 @@ namespace evalhyd
             const std::unordered_map<std::string, int>& bootstrap =
                     {{"n_samples", -9}, {"len_sample", -9}, {"summary", 0}},
             const std::vector<std::string>& dts = {}
-    )
-    {
-        // check that the metrics to be computed are valid
-        utils::check_metrics(
-                metrics,
-                {"RMSE", "NSE", "KGE", "KGEPRIME"}
-        );
-
-        // check that optional parameters are valid
-        eh::utils::check_bootstrap(bootstrap);
-
-        // check that data dimensions are compatible
-        // > time
-        if (q_obs.shape(1) != q_prd.shape(1))
-            throw std::runtime_error(
-                    "observations and predictions feature different "
-                    "temporal lengths"
-            );
-        if (t_msk.size() > 0)
-            if (q_obs.shape(1) != t_msk.shape(1))
-                throw std::runtime_error(
-                        "observations and masks feature different "
-                        "temporal lengths"
-                );
-        if (!dts.empty())
-            if (q_obs.shape(1) != dts.size())
-                throw std::runtime_error(
-                        "observations and datetimes feature different "
-                        "temporal lengths"
-                );
-        // > series
-        if (q_obs.shape(0) != 1)
-            throw std::runtime_error(
-                    "observations contain more than one time series"
-            );
-
-        // retrieve dimensions
-        std::size_t n_tim = q_obs.shape(1);
-        std::size_t n_msk = t_msk.size() > 0 ? t_msk.shape(0) :
-                (m_cdt.size() > 0 ? m_cdt.shape(0) : 1);
-
-        // initialise a mask if none provided
-        // (corresponding to no temporal subset)
-        auto gen_msk = [&]() {
-            // if t_msk provided, it takes priority
-            if (t_msk.size() > 0)
-                return t_msk;
-            // else if m_cdt provided, use them to generate t_msk
-            else if (m_cdt.size() > 0)
-            {
-                xt::xtensor<bool, 2> c_msk = xt::zeros<bool>({n_msk, n_tim});
-
-                for (int m = 0; m < n_msk; m++)
-                    xt::view(c_msk, m) =
-                            eh::masks::generate_mask_from_conditions(
-                                    m_cdt[0], xt::view(q_obs, 0), q_prd
-                            );
-
-                return c_msk;
-            }
-            // if neither t_msk nor m_cdt provided, generate dummy mask
-            else
-                return xt::xtensor<bool, 2>{xt::ones<bool>({std::size_t{1}, n_tim})};
-        };
-
-        auto msk = gen_msk();
-
-        // apply streamflow transformation if requested
-        auto q_transform = [&](const xt::xtensor<double, 2>& q)
-        {
-            if ( transform == "none" || (transform == "pow" && exponent == 1))
-            {
-                return q;
-            }
-            else if ( transform == "sqrt" )
-            {
-                return xt::eval(xt::sqrt(q));
-            }
-            else if ( transform == "inv" )
-            {
-                if ( epsilon == -9 )
-                    // determine an epsilon value to avoid zero divide
-                    epsilon = xt::mean(q_obs)() * 0.01;
-
-                return xt::eval(1. / (q + epsilon));
-            }
-            else if ( transform == "log" )
-            {
-                if ( epsilon == -9 )
-                    // determine an epsilon value to avoid log zero
-                    epsilon = xt::mean(q_obs)() * 0.01;
-
-                return xt::eval(xt::log(q + epsilon));
-            }
-            else if ( transform == "pow" )
-            {
-                if ( exponent < 0 )
-                {
-                    if ( epsilon == -9 )
-                        // determine an epsilon value to avoid zero divide
-                        epsilon = xt::mean(q_obs)() * 0.01;
-
-                    return xt::eval(xt::pow(q + epsilon, exponent));
-                }
-                else
-                {
-                    return xt::eval(xt::pow(q, exponent));
-                }
-            }
-            else
-            {
-                throw std::runtime_error(
-                        "invalid streamflow transformation: " + transform
-                );
-            }
-        };
-
-        auto obs = q_transform(q_obs);
-        auto prd = q_transform(q_prd);
-
-        // generate bootstrap experiment if requested
-        std::vector<xt::xkeep_slice<int>> exp;
-        auto n_samples = bootstrap.find("n_samples")->second;
-        auto len_sample = bootstrap.find("len_sample")->second;
-        if ((n_samples != -9) and (len_sample != -9))
-        {
-            if (dts.empty())
-                throw std::runtime_error(
-                        "bootstrap requested but datetimes not provided"
-                );
-
-            exp = eh::uncertainty::bootstrap(
-                    dts, n_samples, len_sample
-            );
-        }
-        else
-        {
-            // if no bootstrap requested, generate one sample
-            // containing all the time indices once
-            xt::xtensor<int, 1> all = xt::arange(n_tim);
-            exp.push_back(xt::keep(all));
-        }
-
-        // instantiate determinist evaluator
-        eh::determinist::Evaluator evaluator(obs, prd, msk, exp);
-
-        // declare maps for memoisation purposes
-        std::unordered_map<std::string, std::vector<std::string>> elt;
-        std::unordered_map<std::string, std::vector<std::string>> dep;
-
-        // register potentially recurring computation elt across metrics
-        elt["RMSE"] = {"quad_err"};
-        elt["NSE"] = {"mean_obs", "quad_obs", "quad_err"};
-        elt["KGE"] = {"mean_obs", "mean_prd", "quad_obs", "quad_prd",
-                      "r_pearson", "alpha", "bias"};
-        elt["KGEPRIME"] = {"mean_obs", "mean_prd", "quad_obs", "quad_prd",
-                           "r_pearson", "alpha", "bias"};
-
-        // register nested metrics (i.e. metric dependent on another metric)
-        // TODO
-
-        // determine required elt/dep to be pre-computed
-        std::vector<std::string> req_elt;
-        std::vector<std::string> req_dep;
-
-        eh::utils::find_requirements(metrics, elt, dep, req_elt, req_dep);
-
-        // pre-compute required elt
-        for ( const auto& element : req_elt )
-        {
-            if ( element == "mean_obs" )
-                evaluator.calc_mean_obs();
-            else if ( element == "mean_prd" )
-                evaluator.calc_mean_prd();
-            else if ( element == "quad_err" )
-                evaluator.calc_quad_err();
-            else if ( element == "quad_obs" )
-                evaluator.calc_quad_obs();
-            else if ( element == "quad_prd" )
-                evaluator.calc_quad_prd();
-            else if ( element == "r_pearson" )
-                evaluator.calc_r_pearson();
-            else if ( element == "alpha" )
-                evaluator.calc_alpha();
-            else if ( element == "bias" )
-                evaluator.calc_bias();
-        }
-
-        // pre-compute required dep
-        for ( const auto& dependency : req_dep )
-        {
-            // TODO
-        }
-
-        // retrieve or compute requested metrics
-        std::vector<xt::xarray<double>> r;
-
-        auto summary = bootstrap.find("summary")->second;
-
-        for ( const auto& metric : metrics )
-        {
-            if ( metric == "RMSE" )
-            {
-                if (std::find(req_dep.begin(), req_dep.end(), metric)
-                    == req_dep.end())
-                    evaluator.calc_RMSE();
-                r.emplace_back(eh::uncertainty::summarise(evaluator.RMSE, summary));
-            }
-            else if ( metric == "NSE" )
-            {
-                if (std::find(req_dep.begin(), req_dep.end(), metric)
-                        == req_dep.end())
-                    evaluator.calc_NSE();
-                r.emplace_back(eh::uncertainty::summarise(evaluator.NSE, summary));
-            }
-            else if ( metric == "KGE" )
-            {
-                if (std::find(req_dep.begin(), req_dep.end(), metric)
-                    == req_dep.end())
-                    evaluator.calc_KGE();
-                r.emplace_back(eh::uncertainty::summarise(evaluator.KGE, summary));
-            }
-            else if ( metric == "KGEPRIME" )
-            {
-                if (std::find(req_dep.begin(), req_dep.end(), metric)
-                    == req_dep.end())
-                    evaluator.calc_KGEPRIME();
-                r.emplace_back(eh::uncertainty::summarise(evaluator.KGEPRIME, summary));
-            }
-        }
-
-        return r;
-    }
+    );
 }
 
-#endif //EVALHYD_DETERMINIST_HPP
+#endif //EVALHYD_EVALD_HPP
diff --git a/include/evalhyd/evalp.hpp b/include/evalhyd/evalp.hpp
index 5d4c1f00328c0c0edbbe00fc785f007ab50b2f46..6fbce8f1bf4bbbcd6dcc9cf3de92e0bd9c1e93b8 100644
--- a/include/evalhyd/evalp.hpp
+++ b/include/evalhyd/evalp.hpp
@@ -1,22 +1,12 @@
-#ifndef EVALHYD_PROBABILIST_HPP
-#define EVALHYD_PROBABILIST_HPP
+#ifndef EVALHYD_EVALP_HPP
+#define EVALHYD_EVALP_HPP
 
-#include <utility>
 #include <unordered_map>
 #include <vector>
-#include <array>
-#include <stdexcept>
+
 #include <xtensor/xtensor.hpp>
 #include <xtensor/xarray.hpp>
-#include <xtensor/xview.hpp>
-
-#include "../../src/utils.hpp"
-#include "../../src/masks.hpp"
-#include "../../src/maths.hpp"
-#include "../../src/uncertainty.hpp"
-#include "../../src/probabilist/evaluator.h"
 
-namespace eh = evalhyd;
 
 namespace evalhyd
 {
@@ -135,262 +125,7 @@ namespace evalhyd
             const std::unordered_map<std::string, int>& bootstrap =
                     {{"n_samples", -9}, {"len_sample", -9}, {"summary", 0}},
             const std::vector<std::string>& dts = {}
-    )
-    {
-        // check that the metrics to be computed are valid
-        eh::utils::check_metrics(
-                metrics,
-                {"BS", "BSS", "BS_CRD", "BS_LBD", "QS", "CRPS"}
-        );
-
-        // check that optional parameters are given as arguments
-        eh::utils::evalp::check_optionals(metrics, q_thr);
-        eh::utils::check_bootstrap(bootstrap);
-
-        // check that data dimensions are compatible
-        // > time
-        if (q_obs.shape(1) != q_prd.shape(3))
-            throw std::runtime_error(
-                    "observations and predictions feature different "
-                    "temporal lengths"
-            );
-        if (t_msk.size() > 0)
-            if (q_obs.shape(1) != t_msk.shape(3))
-                throw std::runtime_error(
-                        "observations and masks feature different "
-                        "temporal lengths"
-                );
-        if (!dts.empty())
-            if (q_obs.shape(1) != dts.size())
-                throw std::runtime_error(
-                        "observations and datetimes feature different "
-                        "temporal lengths"
-                );
-        // > leadtimes
-        if (t_msk.size() > 0)
-            if (q_prd.shape(1) != t_msk.shape(1))
-                throw std::runtime_error(
-                        "predictions and temporal masks feature different "
-                        "numbers of lead times"
-                );
-        // > sites
-        if (q_obs.shape(0) != q_prd.shape(0))
-            throw std::runtime_error(
-                    "observations and predictions feature different "
-                    "numbers of sites"
-            );
-        if (t_msk.size() > 0)
-            if (q_obs.shape(0) != t_msk.shape(0))
-                throw std::runtime_error(
-                        "observations and temporal masks feature different "
-                        "numbers of sites"
-                );
-        if (m_cdt.size() > 0)
-            if (q_obs.shape(0) != m_cdt.shape(0))
-                throw std::runtime_error(
-                        "observations and masking conditions feature different "
-                        "numbers of sites"
-                );
-
-        // retrieve dimensions
-        std::size_t n_sit = q_prd.shape(0);
-        std::size_t n_ltm = q_prd.shape(1);
-        std::size_t n_mbr = q_prd.shape(2);
-        std::size_t n_tim = q_prd.shape(3);
-        std::size_t n_thr = q_thr.shape(1);
-        std::size_t n_msk = t_msk.size() > 0 ? t_msk.shape(2) :
-                (m_cdt.size() > 0 ? m_cdt.shape(1) : 1);
-        std::size_t n_exp = bootstrap.find("n_samples")->second == -9 ? 1:
-                bootstrap.find("n_samples")->second;
-
-        // register metrics number of dimensions
-        std::unordered_map<std::string, std::vector<std::size_t>> dim;
-
-        dim["BS"] = {n_sit, n_ltm, n_msk, n_exp, n_thr};
-        dim["BSS"] = {n_sit, n_ltm, n_msk, n_exp, n_thr};
-        dim["BS_CRD"] = {n_sit, n_ltm, n_msk, n_exp, n_thr, 3};
-        dim["BS_LBD"] = {n_sit, n_ltm, n_msk, n_exp, n_thr, 3};
-        dim["QS"] = {n_sit, n_ltm, n_msk, n_exp, n_mbr};
-        dim["CRPS"] = {n_sit, n_ltm, n_msk, n_exp};
-
-        // declare maps for memoisation purposes
-        std::unordered_map<std::string, std::vector<std::string>> elt;
-        std::unordered_map<std::string, std::vector<std::string>> dep;
-
-        // register potentially recurring computation elements across metrics
-        elt["bs"] = {"o_k", "y_k"};
-        elt["BSS"] = {"o_k", "bar_o"};
-        elt["BS_CRD"] = {"o_k", "bar_o", "y_k"};
-        elt["BS_LBD"] = {"o_k", "y_k"};
-        elt["qs"] = {"q_qnt"};
-
-        // register nested metrics (i.e. metric dependent on another metric)
-        dep["BS"] = {"bs"};
-        dep["BSS"] = {"bs"};
-        dep["QS"] = {"qs"};
-        dep["CRPS"] = {"qs", "crps"};
-
-        // determine required elt/dep to be pre-computed
-        std::vector<std::string> req_elt;
-        std::vector<std::string> req_dep;
-
-        eh::utils::find_requirements(metrics, elt, dep, req_elt, req_dep);
-
-        // generate masks from conditions if provided
-        auto gen_msk = [&]() {
-            xt::xtensor<bool, 4> c_msk = xt::zeros<bool>({n_sit, n_ltm, n_msk, n_tim});
-            if (m_cdt.size() > 0)
-                for (int s = 0; s < n_sit; s++)
-                    for (int l = 0; l < n_ltm; l++)
-                        for (int m = 0; m < n_msk; m++)
-                            xt::view(c_msk, s, l, m) =
-                                    eh::masks::generate_mask_from_conditions(
-                                            xt::view(m_cdt, s, m),
-                                            xt::view(q_obs, s),
-                                            xt::view(q_prd, s, l)
-                                    );
-            return c_msk;
-        };
-        const xt::xtensor<bool, 4> c_msk = gen_msk();
-
-        // generate bootstrap experiment if requested
-        std::vector<xt::xkeep_slice<int>> b_exp;
-        auto n_samples = bootstrap.find("n_samples")->second;
-        auto len_sample = bootstrap.find("len_sample")->second;
-        if ((n_samples != -9) and (len_sample != -9))
-        {
-            if (dts.empty())
-                throw std::runtime_error(
-                        "bootstrap requested but datetimes not provided"
-                );
-
-            b_exp = eh::uncertainty::bootstrap(
-                    dts, n_samples, len_sample
-            );
-        }
-        else
-        {
-            // if no bootstrap requested, generate one sample
-            // containing all the time indices once
-            xt::xtensor<int, 1> all = xt::arange(n_tim);
-            b_exp.push_back(xt::keep(all));
-        }
-
-        // initialise data structure for outputs
-        std::vector<xt::xarray<double>> r;
-        for (const auto& metric : metrics)
-            r.emplace_back(xt::zeros<double>(dim[metric]));
-
-        auto summary = bootstrap.find("summary")->second;
-
-        // compute variables one site at a time to minimise memory imprint
-        for (int s = 0; s < n_sit; s++)
-            // compute variables one lead time at a time to minimise memory imprint
-            for (int l = 0; l < n_ltm; l++)
-            {
-                // instantiate probabilist evaluator
-                const auto q_obs_v = xt::view(q_obs, s, xt::all());
-                const auto q_prd_v = xt::view(q_prd, s, l, xt::all(), xt::all());
-                const auto q_thr_v = xt::view(q_thr, s, xt::all());
-                const auto t_msk_v =
-                        t_msk.size() > 0 ?
-                        xt::view(t_msk, s, l, xt::all(), xt::all()) :
-                        (m_cdt.size() > 0 ?
-                         xt::view(c_msk, s, l, xt::all(), xt::all()) :
-                         xt::view(t_msk, s, l, xt::all(), xt::all()));
-
-                eh::probabilist::Evaluator evaluator(
-                        q_obs_v, q_prd_v, q_thr_v, t_msk_v, b_exp
-                );
-
-                // pre-compute required elt
-                for (const auto& element : req_elt)
-                {
-                    if ( element == "o_k" )
-                        evaluator.calc_o_k();
-                    else if ( element == "bar_o" )
-                        evaluator.calc_bar_o();
-                    else if ( element == "y_k" )
-                        evaluator.calc_y_k();
-                    else if ( element == "q_qnt" )
-                        evaluator.calc_q_qnt();
-                }
-
-                // pre-compute required dep
-                for (const auto& dependency : req_dep)
-                {
-                    if ( dependency == "bs" )
-                        evaluator.calc_bs();
-                    else if ( dependency == "qs" )
-                        evaluator.calc_qs();
-                    else if ( dependency == "crps" )
-                        evaluator.calc_crps();
-                }
-
-                // retrieve or compute requested metrics
-                for (int m = 0; m < metrics.size(); m++)
-                {
-                    const auto& metric = metrics[m];
-
-                    if ( metric == "BS" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_BS();
-                        // (sites, lead times, subsets, samples, thresholds)
-                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.BS, summary);
-                    }
-                    else if ( metric == "BSS" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_BSS();
-                        // (sites, lead times, subsets, samples, thresholds)
-                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.BSS, summary);
-                    }
-                    else if ( metric == "BS_CRD" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_BS_CRD();
-                        // (sites, lead times, subsets, samples, thresholds, components)
-                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.BS_CRD, summary);
-                    }
-                    else if ( metric == "BS_LBD" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_BS_LBD();
-                        // (sites, lead times, subsets, samples, thresholds, components)
-                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.BS_LBD, summary);
-                    }
-                    else if ( metric == "QS" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_QS();
-                        // (sites, lead times, subsets, samples, quantiles)
-                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.QS, summary);
-                    }
-                    else if ( metric == "CRPS" )
-                    {
-                        if (std::find(req_dep.begin(), req_dep.end(), metric)
-                            == req_dep.end())
-                            evaluator.calc_CRPS();
-                        // (sites, lead times, subsets, samples)
-                        xt::view(r[m], s, l, xt::all(), xt::all()) =
-                                eh::uncertainty::summarise(evaluator.CRPS, summary);
-                    }
-                }
-            }
-
-        return r;
-    }
+    );
 }
 
-#endif //EVALHYD_PROBABILIST_HPP
+#endif //EVALHYD_EVALP_HPP
diff --git a/src/determinist/evald.cpp b/src/determinist/evald.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b39dd1484fc9ad2c48e76802d19a96c9174fcf51
--- /dev/null
+++ b/src/determinist/evald.cpp
@@ -0,0 +1,264 @@
+#include <unordered_map>
+#include <vector>
+#include <array>
+#include <stdexcept>
+#include <xtensor/xexpression.hpp>
+#include <xtensor/xarray.hpp>
+#include <xtensor/xscalar.hpp>
+
+#include "../utils.hpp"
+#include "../masks.hpp"
+#include "../maths.hpp"
+#include "../uncertainty.hpp"
+#include "evaluator.hpp"
+
+namespace eh = evalhyd;
+
+namespace evalhyd
+{
+    std::vector<xt::xarray<double>> evald(
+            const xt::xtensor<double, 2>& q_obs,
+            const xt::xtensor<double, 2>& q_prd,
+            const std::vector<std::string>& metrics,
+            const std::string& transform = "none",
+            const double exponent = 1,
+            double epsilon = -9,
+            const xt::xtensor<bool, 2>& t_msk = {},
+            const xt::xtensor<std::array<char, 32>, 1>& m_cdt = {},
+            const std::unordered_map<std::string, int>& bootstrap =
+                    {{"n_samples", -9}, {"len_sample", -9}, {"summary", 0}},
+            const std::vector<std::string>& dts = {}
+    )
+    {
+        // check that the metrics to be computed are valid
+        utils::check_metrics(
+                metrics,
+                {"RMSE", "NSE", "KGE", "KGEPRIME"}
+        );
+
+        // check that optional parameters are valid
+        eh::utils::check_bootstrap(bootstrap);
+
+        // check that data dimensions are compatible
+        // > time
+        if (q_obs.shape(1) != q_prd.shape(1))
+            throw std::runtime_error(
+                    "observations and predictions feature different "
+                    "temporal lengths"
+            );
+        if (t_msk.size() > 0)
+            if (q_obs.shape(1) != t_msk.shape(1))
+                throw std::runtime_error(
+                        "observations and masks feature different "
+                        "temporal lengths"
+                );
+        if (!dts.empty())
+            if (q_obs.shape(1) != dts.size())
+                throw std::runtime_error(
+                        "observations and datetimes feature different "
+                        "temporal lengths"
+                );
+        // > series
+        if (q_obs.shape(0) != 1)
+            throw std::runtime_error(
+                    "observations contain more than one time series"
+            );
+
+        // retrieve dimensions
+        std::size_t n_tim = q_obs.shape(1);
+        std::size_t n_msk = t_msk.size() > 0 ? t_msk.shape(0) :
+                            (m_cdt.size() > 0 ? m_cdt.shape(0) : 1);
+
+        // initialise a mask if none provided
+        // (corresponding to no temporal subset)
+        auto gen_msk = [&]() {
+            // if t_msk provided, it takes priority
+            if (t_msk.size() > 0)
+                return t_msk;
+                // else if m_cdt provided, use them to generate t_msk
+            else if (m_cdt.size() > 0)
+            {
+                xt::xtensor<bool, 2> c_msk = xt::zeros<bool>({n_msk, n_tim});
+
+                for (int m = 0; m < n_msk; m++)
+                    xt::view(c_msk, m) =
+                            eh::masks::generate_mask_from_conditions(
+                                    m_cdt[0], xt::view(q_obs, 0), q_prd
+                            );
+
+                return c_msk;
+            }
+                // if neither t_msk nor m_cdt provided, generate dummy mask
+            else
+                return xt::xtensor<bool, 2>{xt::ones<bool>({std::size_t{1}, n_tim})};
+        };
+
+        auto msk = gen_msk();
+
+        // apply streamflow transformation if requested
+        auto q_transform = [&](const xt::xtensor<double, 2>& q)
+        {
+            if ( transform == "none" || (transform == "pow" && exponent == 1))
+            {
+                return q;
+            }
+            else if ( transform == "sqrt" )
+            {
+                return xt::eval(xt::sqrt(q));
+            }
+            else if ( transform == "inv" )
+            {
+                if ( epsilon == -9 )
+                    // determine an epsilon value to avoid zero divide
+                    epsilon = xt::mean(q_obs)() * 0.01;
+
+                return xt::eval(1. / (q + epsilon));
+            }
+            else if ( transform == "log" )
+            {
+                if ( epsilon == -9 )
+                    // determine an epsilon value to avoid log zero
+                    epsilon = xt::mean(q_obs)() * 0.01;
+
+                return xt::eval(xt::log(q + epsilon));
+            }
+            else if ( transform == "pow" )
+            {
+                if ( exponent < 0 )
+                {
+                    if ( epsilon == -9 )
+                        // determine an epsilon value to avoid zero divide
+                        epsilon = xt::mean(q_obs)() * 0.01;
+
+                    return xt::eval(xt::pow(q + epsilon, exponent));
+                }
+                else
+                {
+                    return xt::eval(xt::pow(q, exponent));
+                }
+            }
+            else
+            {
+                throw std::runtime_error(
+                        "invalid streamflow transformation: " + transform
+                );
+            }
+        };
+
+        auto obs = q_transform(q_obs);
+        auto prd = q_transform(q_prd);
+
+        // generate bootstrap experiment if requested
+        std::vector<xt::xkeep_slice<int>> exp;
+        auto n_samples = bootstrap.find("n_samples")->second;
+        auto len_sample = bootstrap.find("len_sample")->second;
+        if ((n_samples != -9) and (len_sample != -9))
+        {
+            if (dts.empty())
+                throw std::runtime_error(
+                        "bootstrap requested but datetimes not provided"
+                );
+
+            exp = eh::uncertainty::bootstrap(
+                    dts, n_samples, len_sample
+            );
+        }
+        else
+        {
+            // if no bootstrap requested, generate one sample
+            // containing all the time indices once
+            xt::xtensor<int, 1> all = xt::arange(n_tim);
+            exp.push_back(xt::keep(all));
+        }
+
+        // instantiate determinist evaluator
+        eh::determinist::Evaluator evaluator(obs, prd, msk, exp);
+
+        // declare maps for memoisation purposes
+        std::unordered_map<std::string, std::vector<std::string>> elt;
+        std::unordered_map<std::string, std::vector<std::string>> dep;
+
+        // register potentially recurring computation elt across metrics
+        elt["RMSE"] = {"quad_err"};
+        elt["NSE"] = {"mean_obs", "quad_obs", "quad_err"};
+        elt["KGE"] = {"mean_obs", "mean_prd", "quad_obs", "quad_prd",
+                      "r_pearson", "alpha", "bias"};
+        elt["KGEPRIME"] = {"mean_obs", "mean_prd", "quad_obs", "quad_prd",
+                           "r_pearson", "alpha", "bias"};
+
+        // register nested metrics (i.e. metric dependent on another metric)
+        // TODO
+
+        // determine required elt/dep to be pre-computed
+        std::vector<std::string> req_elt;
+        std::vector<std::string> req_dep;
+
+        eh::utils::find_requirements(metrics, elt, dep, req_elt, req_dep);
+
+        // pre-compute required elt
+        for ( const auto& element : req_elt )
+        {
+            if ( element == "mean_obs" )
+                evaluator.calc_mean_obs();
+            else if ( element == "mean_prd" )
+                evaluator.calc_mean_prd();
+            else if ( element == "quad_err" )
+                evaluator.calc_quad_err();
+            else if ( element == "quad_obs" )
+                evaluator.calc_quad_obs();
+            else if ( element == "quad_prd" )
+                evaluator.calc_quad_prd();
+            else if ( element == "r_pearson" )
+                evaluator.calc_r_pearson();
+            else if ( element == "alpha" )
+                evaluator.calc_alpha();
+            else if ( element == "bias" )
+                evaluator.calc_bias();
+        }
+
+        // pre-compute required dep
+        for ( const auto& dependency : req_dep )
+        {
+            // TODO
+        }
+
+        // retrieve or compute requested metrics
+        std::vector<xt::xarray<double>> r;
+
+        auto summary = bootstrap.find("summary")->second;
+
+        for ( const auto& metric : metrics )
+        {
+            if ( metric == "RMSE" )
+            {
+                if (std::find(req_dep.begin(), req_dep.end(), metric)
+                    == req_dep.end())
+                    evaluator.calc_RMSE();
+                r.emplace_back(eh::uncertainty::summarise(evaluator.RMSE, summary));
+            }
+            else if ( metric == "NSE" )
+            {
+                if (std::find(req_dep.begin(), req_dep.end(), metric)
+                    == req_dep.end())
+                    evaluator.calc_NSE();
+                r.emplace_back(eh::uncertainty::summarise(evaluator.NSE, summary));
+            }
+            else if ( metric == "KGE" )
+            {
+                if (std::find(req_dep.begin(), req_dep.end(), metric)
+                    == req_dep.end())
+                    evaluator.calc_KGE();
+                r.emplace_back(eh::uncertainty::summarise(evaluator.KGE, summary));
+            }
+            else if ( metric == "KGEPRIME" )
+            {
+                if (std::find(req_dep.begin(), req_dep.end(), metric)
+                    == req_dep.end())
+                    evaluator.calc_KGEPRIME();
+                r.emplace_back(eh::uncertainty::summarise(evaluator.KGEPRIME, summary));
+            }
+        }
+
+        return r;
+    }
+}
diff --git a/src/probabilist/evalp.cpp b/src/probabilist/evalp.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..71f2e3800655bb836b1c7a8aaa2be7997df719a6
--- /dev/null
+++ b/src/probabilist/evalp.cpp
@@ -0,0 +1,286 @@
+#include <utility>
+#include <unordered_map>
+#include <vector>
+#include <array>
+#include <stdexcept>
+#include <xtensor/xtensor.hpp>
+#include <xtensor/xarray.hpp>
+#include <xtensor/xview.hpp>
+
+#include "../utils.hpp"
+#include "../masks.hpp"
+#include "../maths.hpp"
+#include "../uncertainty.hpp"
+#include "evaluator.h"
+
+namespace eh = evalhyd;
+
+namespace evalhyd
+{
+    std::vector<xt::xarray<double>> evalp(
+            const xt::xtensor<double, 2>& q_obs,
+            const xt::xtensor<double, 4>& q_prd,
+            const std::vector<std::string>& metrics,
+            const xt::xtensor<double, 2>& q_thr = {},
+            const xt::xtensor<bool, 4>& t_msk = {},
+            const xt::xtensor<std::array<char, 32>, 2>& m_cdt = {},
+            const std::unordered_map<std::string, int>& bootstrap =
+                    {{"n_samples", -9}, {"len_sample", -9}, {"summary", 0}},
+            const std::vector<std::string>& dts = {}
+    )
+    {
+        // check that the metrics to be computed are valid
+        eh::utils::check_metrics(
+                metrics,
+                {"BS", "BSS", "BS_CRD", "BS_LBD", "QS", "CRPS"}
+        );
+
+        // check that optional parameters are given as arguments
+        eh::utils::evalp::check_optionals(metrics, q_thr);
+        eh::utils::check_bootstrap(bootstrap);
+
+        // check that data dimensions are compatible
+        // > time
+        if (q_obs.shape(1) != q_prd.shape(3))
+            throw std::runtime_error(
+                    "observations and predictions feature different "
+                    "temporal lengths"
+            );
+        if (t_msk.size() > 0)
+            if (q_obs.shape(1) != t_msk.shape(3))
+                throw std::runtime_error(
+                        "observations and masks feature different "
+                        "temporal lengths"
+                );
+        if (!dts.empty())
+            if (q_obs.shape(1) != dts.size())
+                throw std::runtime_error(
+                        "observations and datetimes feature different "
+                        "temporal lengths"
+                );
+        // > leadtimes
+        if (t_msk.size() > 0)
+            if (q_prd.shape(1) != t_msk.shape(1))
+                throw std::runtime_error(
+                        "predictions and temporal masks feature different "
+                        "numbers of lead times"
+                );
+        // > sites
+        if (q_obs.shape(0) != q_prd.shape(0))
+            throw std::runtime_error(
+                    "observations and predictions feature different "
+                    "numbers of sites"
+            );
+        if (t_msk.size() > 0)
+            if (q_obs.shape(0) != t_msk.shape(0))
+                throw std::runtime_error(
+                        "observations and temporal masks feature different "
+                        "numbers of sites"
+                );
+        if (m_cdt.size() > 0)
+            if (q_obs.shape(0) != m_cdt.shape(0))
+                throw std::runtime_error(
+                        "observations and masking conditions feature different "
+                        "numbers of sites"
+                );
+
+        // retrieve dimensions
+        std::size_t n_sit = q_prd.shape(0);
+        std::size_t n_ltm = q_prd.shape(1);
+        std::size_t n_mbr = q_prd.shape(2);
+        std::size_t n_tim = q_prd.shape(3);
+        std::size_t n_thr = q_thr.shape(1);
+        std::size_t n_msk = t_msk.size() > 0 ? t_msk.shape(2) :
+                            (m_cdt.size() > 0 ? m_cdt.shape(1) : 1);
+        std::size_t n_exp = bootstrap.find("n_samples")->second == -9 ? 1:
+                            bootstrap.find("n_samples")->second;
+
+        // register metrics number of dimensions
+        std::unordered_map<std::string, std::vector<std::size_t>> dim;
+
+        dim["BS"] = {n_sit, n_ltm, n_msk, n_exp, n_thr};
+        dim["BSS"] = {n_sit, n_ltm, n_msk, n_exp, n_thr};
+        dim["BS_CRD"] = {n_sit, n_ltm, n_msk, n_exp, n_thr, 3};
+        dim["BS_LBD"] = {n_sit, n_ltm, n_msk, n_exp, n_thr, 3};
+        dim["QS"] = {n_sit, n_ltm, n_msk, n_exp, n_mbr};
+        dim["CRPS"] = {n_sit, n_ltm, n_msk, n_exp};
+
+        // declare maps for memoisation purposes
+        std::unordered_map<std::string, std::vector<std::string>> elt;
+        std::unordered_map<std::string, std::vector<std::string>> dep;
+
+        // register potentially recurring computation elements across metrics
+        elt["bs"] = {"o_k", "y_k"};
+        elt["BSS"] = {"o_k", "bar_o"};
+        elt["BS_CRD"] = {"o_k", "bar_o", "y_k"};
+        elt["BS_LBD"] = {"o_k", "y_k"};
+        elt["qs"] = {"q_qnt"};
+
+        // register nested metrics (i.e. metric dependent on another metric)
+        dep["BS"] = {"bs"};
+        dep["BSS"] = {"bs"};
+        dep["QS"] = {"qs"};
+        dep["CRPS"] = {"qs", "crps"};
+
+        // determine required elt/dep to be pre-computed
+        std::vector<std::string> req_elt;
+        std::vector<std::string> req_dep;
+
+        eh::utils::find_requirements(metrics, elt, dep, req_elt, req_dep);
+
+        // generate masks from conditions if provided
+        auto gen_msk = [&]() {
+            xt::xtensor<bool, 4> c_msk = xt::zeros<bool>({n_sit, n_ltm, n_msk, n_tim});
+            if (m_cdt.size() > 0)
+                for (int s = 0; s < n_sit; s++)
+                    for (int l = 0; l < n_ltm; l++)
+                        for (int m = 0; m < n_msk; m++)
+                            xt::view(c_msk, s, l, m) =
+                                    eh::masks::generate_mask_from_conditions(
+                                            xt::view(m_cdt, s, m),
+                                            xt::view(q_obs, s),
+                                            xt::view(q_prd, s, l)
+                                    );
+            return c_msk;
+        };
+        const xt::xtensor<bool, 4> c_msk = gen_msk();
+
+        // generate bootstrap experiment if requested
+        std::vector<xt::xkeep_slice<int>> b_exp;
+        auto n_samples = bootstrap.find("n_samples")->second;
+        auto len_sample = bootstrap.find("len_sample")->second;
+        if ((n_samples != -9) and (len_sample != -9))
+        {
+            if (dts.empty())
+                throw std::runtime_error(
+                        "bootstrap requested but datetimes not provided"
+                );
+
+            b_exp = eh::uncertainty::bootstrap(
+                    dts, n_samples, len_sample
+            );
+        }
+        else
+        {
+            // if no bootstrap requested, generate one sample
+            // containing all the time indices once
+            xt::xtensor<int, 1> all = xt::arange(n_tim);
+            b_exp.push_back(xt::keep(all));
+        }
+
+        // initialise data structure for outputs
+        std::vector<xt::xarray<double>> r;
+        for (const auto& metric : metrics)
+            r.emplace_back(xt::zeros<double>(dim[metric]));
+
+        auto summary = bootstrap.find("summary")->second;
+
+        // compute variables one site at a time to minimise memory imprint
+        for (int s = 0; s < n_sit; s++)
+            // compute variables one lead time at a time to minimise memory imprint
+            for (int l = 0; l < n_ltm; l++)
+            {
+                // instantiate probabilist evaluator
+                const auto q_obs_v = xt::view(q_obs, s, xt::all());
+                const auto q_prd_v = xt::view(q_prd, s, l, xt::all(), xt::all());
+                const auto q_thr_v = xt::view(q_thr, s, xt::all());
+                const auto t_msk_v =
+                        t_msk.size() > 0 ?
+                        xt::view(t_msk, s, l, xt::all(), xt::all()) :
+                        (m_cdt.size() > 0 ?
+                         xt::view(c_msk, s, l, xt::all(), xt::all()) :
+                         xt::view(t_msk, s, l, xt::all(), xt::all()));
+
+                eh::probabilist::Evaluator evaluator(
+                        q_obs_v, q_prd_v, q_thr_v, t_msk_v, b_exp
+                );
+
+                // pre-compute required elt
+                for (const auto& element : req_elt)
+                {
+                    if ( element == "o_k" )
+                        evaluator.calc_o_k();
+                    else if ( element == "bar_o" )
+                        evaluator.calc_bar_o();
+                    else if ( element == "y_k" )
+                        evaluator.calc_y_k();
+                    else if ( element == "q_qnt" )
+                        evaluator.calc_q_qnt();
+                }
+
+                // pre-compute required dep
+                for (const auto& dependency : req_dep)
+                {
+                    if ( dependency == "bs" )
+                        evaluator.calc_bs();
+                    else if ( dependency == "qs" )
+                        evaluator.calc_qs();
+                    else if ( dependency == "crps" )
+                        evaluator.calc_crps();
+                }
+
+                // retrieve or compute requested metrics
+                for (int m = 0; m < metrics.size(); m++)
+                {
+                    const auto& metric = metrics[m];
+
+                    if ( metric == "BS" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_BS();
+                        // (sites, lead times, subsets, samples, thresholds)
+                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.BS, summary);
+                    }
+                    else if ( metric == "BSS" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_BSS();
+                        // (sites, lead times, subsets, samples, thresholds)
+                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.BSS, summary);
+                    }
+                    else if ( metric == "BS_CRD" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_BS_CRD();
+                        // (sites, lead times, subsets, samples, thresholds, components)
+                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.BS_CRD, summary);
+                    }
+                    else if ( metric == "BS_LBD" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_BS_LBD();
+                        // (sites, lead times, subsets, samples, thresholds, components)
+                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.BS_LBD, summary);
+                    }
+                    else if ( metric == "QS" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_QS();
+                        // (sites, lead times, subsets, samples, quantiles)
+                        xt::view(r[m], s, l, xt::all(), xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.QS, summary);
+                    }
+                    else if ( metric == "CRPS" )
+                    {
+                        if (std::find(req_dep.begin(), req_dep.end(), metric)
+                            == req_dep.end())
+                            evaluator.calc_CRPS();
+                        // (sites, lead times, subsets, samples)
+                        xt::view(r[m], s, l, xt::all(), xt::all()) =
+                                eh::uncertainty::summarise(evaluator.CRPS, summary);
+                    }
+                }
+            }
+
+        return r;
+    }
+}